JPS631838B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a motor fixed position stopping device for stopping a motor at a predetermined rotational position.

Conventional technology Conventionally, when stopping a motor at a fixed position,
The rotational position is detected by a detection signal for rotational position detection, and based on the detection signal, the motor The brake was applied to stop the motor at a predetermined rotational position.

However, in the case of the above method, if the motor is always driven at a constant rotational speed, it is possible to accurately stop the motor at a predetermined rotational position.
If the rotational speed of the motor is constantly fluctuating, or if the rotational speed varies even though the motor is driven at a constant speed, the motor will not be stopped at a predetermined rotational position. There was a defect in which the machine stopped before a predetermined rotational position or overran.

Therefore, there has been a problem in that accurate and safe sewing operations cannot be performed, for example, in sewing machines that require the motor to stop at an accurate fixed position.

Objective: This invention eliminates the above-mentioned defects and provides a fixed position stopping device for a motor that can always stop the motor at a predetermined rotational position without variations in stopping at a predetermined rotational position due to fluctuations in the rotational speed of the motor. is to provide.

Embodiment Hereinafter, an embodiment in which a fixed position stop device for a motor according to the present invention is implemented in a sewing machine will be described based on the drawings.

1 is a sewing machine table, 2 is a sewing machine body placed on the sewing machine table 1, and a bracket 3 is attached to one side. M is a direct current motor (hereinafter referred to as the motor) for driving the sewing machine that is fixedly installed on one side of the upper part of the bracket 3, and as shown in FIG. connected.

Reference numeral 6 denotes a holder attached to the bracket part Mb of the motor M, and as shown by the two-dot chain line in FIG. A sensor 8 for detecting a shift point and a sensor 9 for detecting a shift point are mounted to face the pulley 4. Reference numeral 10 denotes a holder attached to the inner surface of the bracket 3 by bolts 11, and a part of the holder 10 is inserted into an arc-shaped elongated hole 12 transparently provided in the bracket 3, as shown by the two-dot chain line in FIG. They are fitted together, and the mounting position can be adjusted by moving around the rotational axis of the motor shaft Ma.

Reference numeral 13 denotes a needle top position detection sensor attached to the pulley side of the distal end of the holder 10, and is composed of a Hall element. As shown in FIG. 3, a magnet 14 is attached to the blade portion 4a of the pulley 4 to detect the needle down position. , the magnet 14 is arranged relative to the needle down position detecting sensor 7 so as to rotate through the opposite position closest to the needle down position detecting sensor 7. 1
Reference numeral 6 denotes a thread trimming signal detection magnet which is also attached to the blade portion 4a of the pulley 4. When the needle 15 moves up and down and comes to the thread trimming position, the magnet 16 detects the thread trimming sensor 8. They are arranged relative to each other so as to rotate and pass through the closest opposing position. 17a, 17
Similarly, reference numeral b denotes a pair of magnets attached to the blade portion 4a of the pulley 4. When the needle 15 moves up and down and comes to the needle upper position, one of the magnets 17a is connected to the needle upper position detection sensor 13, which is closest to the needle upper position detection sensor 13. It rotates through a nearby opposing position,
Subsequently, the other magnet 17b is arranged relative to the sensor 13 so as to rotate and pass through it. A magnet 18 is similarly attached to the boss portion 4b of the pulley 4, and is relatively arranged so as to rotate through a position facing the shift point detection sensor 9 and close to it.

As mentioned above, both the needle down position detection sensor 7 and the thread trimming sensor 8 are arranged at positions corresponding to the rotation loci of the needle down position detection magnet 14 and the thread trimming magnet 16, but these magnets 14,16
The sensors 7 and 8 are arranged so that the directions of their magnetic fields are opposite to each other, and the sensors 7 and 8 are arranged so that the directions of their sensitive magnetic fields are opposite to each other. does not operate when the thread cutting magnet 16 rotates and passes, and the thread trimming sensor 8 does not operate when the needle down position detection magnet 14 rotates and passes.

And each of these magnets 14, 16, 17a, 1
7b, 18 rotate to each corresponding sensor 7,
8, 9, and 13, the needle down detection signal NLDN of zero potential (hereinafter referred to as L level) is sent from the needle down position detection sensor 7, the thread trimming signal NLTC of L level is sent from the thread trimming sensor 8, and the shift point is detected. The shift point signal NLCV at the L level is output from the shift point signal NLCV at the L level, and the first and second needle up detection signals NLUP at the L level are output from the needle up position detection sensor 13. In addition, each sensor 7, 8,
9 and 10 are magnets 14, 16, 17a and 1, respectively.
When 7b and 18 do not rotate, a detection signal of positive potential (hereinafter referred to as H level) is output.

SW1 is the sewing machine table 1 as shown in Figure 1.
The starting switch SW2 is a stop switch provided on the right side of the starting switch SW1. CB is a control box attached to the lower left side of the sewing machine table 1 via a support arm 19, and contains an electric circuit for driving and controlling the sewing machine, which will be described later. Reference numeral 20 is a front backtack setting switch that is installed on the front of the control box CB and determines whether or not to perform front backtack stitching, and below it is a digital switch for setting the number of stitches that determines the number of stitches to be stitched when sewing the front backtack. A switch 21 is provided. Reference numeral 22 denotes a switch for setting the end backtack stitch, which determines whether or not to perform the end backtack stitching process, and a digital switch for setting the number of stitches that determines the number of stitches for end backtitching is provided below it. RB is a maximum speed adjustment volume provided on the right side of the digital switch 23 for setting the number of stitches, and the upper limit of the rotational speed of the motor M is set.

PD is a pedal installed below the sewing machine table 1, and as shown in Fig. 4, the pedal
When the front end of the PD is depressed downward from the neutral position area, the pedal PD
is moved to the presser foot area, the first speed area of the front depressing area, and the pedal command speed area (second speed area). On the other hand, when the rear end side of the pedal PD is depressed downward, the pedal PD is moved to the rear depressing area. It is starting to be moved to

Reference numeral 24 is a connecting rod whose lower end is connected to the pedal PD and whose upper end is connected to a potentiometer POT (to be described later) in the control box CB. It's getting old. When the pedal PD is depressed, the potentiometer POT outputs an output signal corresponding to the amount of depression of the pedal PD via the connecting rod 24.

Next, a fixed position stopping device for a sewing machine motor constructed as described above will be explained based on the electric block circuit diagram shown in FIG.

31 is a speed command voltage generation circuit into which the output voltage from the potentiometer POT linked with the pedal PD and the output voltage from the maximum speed adjustment volume RB are input,
p・m, 500r・p・m, 300r・p・m and 200r・
Speed command voltages C1500, C500, C300, with preset values for speed control to the rotation speed of p・m
C200 is output. Further, the generating circuit 31 outputs control signals BACK, UPCL, FRNT, and F2UP for detecting a pedal depression position corresponding to the depression amount of the pedal PD to a control circuit 38, which will be described later, via the potentiometer POT.

32 is a selector circuit to which the speed command voltages CPED, C1500, C500, C300, and C200 are input from the speed command voltage generation circuit 31, and each speed command voltage is inputted based on a selection control signal SG1 from the control circuit 38, which will be described later. CPED，C1500，C500，C300，
Select and output one command voltage from C200.

33 is a selected speed command voltage from the selector circuit 32 and a speed voltage VS proportional to the rotational speed of the motor M from a speed voltage detection circuit 35 to be described later.
is a speed control circuit to which motor M
The actual rotational speed of the motor M is compared with the rotational speed based on the selected speed command voltage, and a speed command signal SG2 for setting the motor M to the selected rotational speed is output.

34 is a motor drive current supply circuit that supplies a drive current to the motor M, and the speed control circuit 33
Based on the speed command signal SG2 from the motor M
turning on and off a drive current for driving the motor M, supplying the drive current to the motor M so that the rotational speed of the motor M becomes the selected rotational speed, and supplying the drive current in the opposite direction to the above-mentioned direction. The motor is supplied to the motor M, and the motor M is controlled to stop by applying reverse phase braking to the motor M.

35 is a speed voltage detection circuit for detecting the rotational speed of the motor M, which outputs a voltage proportional to the rotational speed of the motor M (back electromotive voltage) as the speed voltage VS to the speed control circuit 33, and also as described below. Output to control circuit 38.

Reference numeral 36 denotes a sewing machine operating position detection circuit, which is composed of sensors 7, 8, 9, and 13 for detecting the needle down position, thread trimming, gear shift point detection, and needle up position detection. Signal NLDN, thread trimming signal
NLTC, shift point signal NLCV, needle top detection signal
NLUP is output to a control circuit 38, which will be described later.

Reference numeral 37 is a backtack and stitch number setting circuit, which is comprised of the front and end backtack setting switches 20, 22, digital switches 21, 23, etc. for setting the number of stitches, and sets the presence or absence of backtack stitches and the number of backtack stitches. A control signal is output to a control circuit 38, which will be described later.

Reference numeral 38 denotes a control circuit to which the control signals and detection signals are inputted from the speed command voltage generation circuit 31, speed voltage detection circuit 35, sewing machine operating position detection circuit 36, etc., and includes a central processing unit, a readout memory (Read Only It consists of a microcomputer consisting of a readable/writable memory (Random Access Memory), and an input/output port, and various input/output ports are connected to the input/output port according to a control program stored in advance in the read-only memory. It is designed to control output devices. The speed command voltage generation circuit 31
A control signal based on the operation of said pedal PD from
BACK, UPCL, FRNT, F2UP and the needle down detection signal from the sewing machine operating position detection circuit 36
NLDN, thread trimming signal NLTC, shift point signal NLCV
Based on the needle up detection signal NLUP, the control circuit 38 sends a selection control signal to the selector circuit 32.
SG1 is output, and the speed command voltage CPED,
One of the speed command voltages C1500, C500, C300, and C200 is selected by the selector circuit 32, and the motor M is driven and controlled to the selected rotational speed. Similarly, a control signal SG3 is output to the motor drive current supply circuit 34, and the drive current supply circuit 34 supplies the motor M with a drive current in the opposite direction to the direction used when driving the motor M. Apply phase control to stop control.

Next, the operation of the fixed position stopping device for the sewing machine motor constructed as described above will be explained with reference to FIGS. 6 to 12.

First, when the sewing on the work cloth is nearing the end (at this time, the pedal PD is depressed in the pedal command speed region of the front depression region, and the motor M is rotated at high speed based on the pedal speed command voltage CPED), the worker When the pedal PD is released to the neutral position area, the program executes check routine 4 to determine whether the pedal PD has been released to the neutral position area according to the flowchart shown in FIG.
From 1, motor M is rotated at high speed to 500r・p・
m, and reaches address A through a routine 42 that decelerates to 200 r.p.m. Furthermore, the program goes through a check routine 43 that determines whether there is a fall signal of the needle down detection signal NLDN generated from the needle down position detection sensor 7 based on the rotating passage of the needle down position detection magnet 14, and then returns to A. It continues to go around the loop (200r/p/m low speed drive loop) that returns to the address. Therefore, the motor M is driven at a low speed (200 r.p.m.) while the program continues to cycle through the above-described loop.

During low speed driving (200r/p/m), the needle down detection signal NLDN accompanying the rotation of the motor M
When a falling signal from the H level to the L level is detected, the program passes through a routine 44 that presets a predetermined time in the timer counter of the microcomputer, and then causes the needle down detection signal to fall from the L level to the H level. A check routine 45 for determining the presence or absence of a rising rising signal of the motor M;
Routine 4 to release the rotation speed of 200r/p/m
6. A check routine 48 is reached to apply anti-phase braking to stop the motor M, and a check routine 48 is reached to determine whether the timer counter has timed up.
Then, the routine 49 for releasing the anti-phase braking is reached, and the motor M stops the needle 15 at the needle down position.

That is, as shown in FIG. 7, a timer counter in the microcomputer of the control circuit 38 is operated for a predetermined period of time by a check routine 47 that detects the fall of the needle down detection signal NLDN from the H level to the L level. Then, a check routine 45 that detects the rise of the needle down detection signal NLDN from the L level to the H level sends the speed command voltage from the control circuit 38 to the selector circuit 32.
A selection control signal SG1 that deselects C200 is output, its speed command voltage C200 is canceled, and a control signal SG that applies anti-phase braking to the motor M is output.
3 is output to the motor drive current supply circuit 34, and anti-phase braking is started. When determining that the timer counter has timed up, the check routine 48 causes the control circuit 38 to output a control signal SG3 to the motor drive current supply circuit 34, which cancels the negative phase braking and does not supply drive current to the motor M. , controls the motor M so that the needle 15 is stopped at the needle down position.

Therefore, when the motor M starts to stop, the motor M
Even if there is a fluctuation in the rotational speed of 200 r.p.m., the reverse phase braking time changes according to the fluctuation, so the motor M can always be stopped at the needle down position. In other words, if the rotational speed of the motor M exceeds 200rpm for some reason, the needle down detection signal NLDN will be activated as shown by the chain line in Figure 8.
As the falling time T1 becomes shorter, the anti-phase braking starts earlier, and the anti-phase braking is completed as the timer set for the predetermined time T2 expires, so the braking time T3 becomes longer and the needle 15 moves from the needle down position to the end of the anti-phase braking. It is possible to reliably stop the needle at the same lower position without overrun. In addition, if the rotational speed of the motor M is below 200rpm for some reason, the fall time T1 of the needle down detection signal NLDN becomes longer, as shown by the solid line in Figure 8, and the reverse occurs. Since the start of phase braking is delayed and the reverse phase braking is completed when the timer counter set to the predetermined time T2 times up, the braking time T6 becomes short, and the reverse phase braking is applied too much, causing the motor M to rotate in the reverse direction. The needle 15 can be reliably stopped at the needle-down position without any problems.

When the sewing machine is stopped at the needle down position, the program reaches address B through a routine 50 for raising the presser foot. Next, when the operator depresses the pedal PD after the pedal PD, the program starts
From the check routine 51 that determines whether or not the backtack has been pressed, the end backtack processing routine 52 is reached, where the end backtack setting switch 22 is set to ON (end backtack is present).
If so, the motor M is driven at a fastening speed of 1500 r/p/m, and after sewing the number of stitches set by the digital switches 21 and 23 for setting the number of stitches, the motor M is rotated. The speed is
The speed is reduced from 1500 r.p.m to 200 r.p.m.
Further, in the case of no backtack stitching, the same routine 52 rotates the motor M at a rotational speed of 200 r.p.m.

Then, the program operates a thread trimming mechanism that is rotationally driven in accordance with the rotation of a shuttle drive shaft (not shown) operatively connected to the motor M and the main shaft 5 of the sewing machine, and captures the upper thread and lower thread from the start of operation. sometimes
200r・p・m, when cutting the upper thread and lower thread
The thread cutting control routine 53 accelerates the rotation speed of the motor M from 200 r.p.m to 300 r.p.m so that the motor M is rotationally driven from 200 r.p.m to 300 r.p.m. A first needle-up detection signal is generated from the needle-up position detection sensor 13 based on the rotating passage of the needle-up position detection magnet 17a.
The loop (300 r.p.m. constant speed drive loop) continues to return to address C from the check routine 54 that determines whether there is a falling signal from the H level to the L level of NLUP. Therefore, while the program continues to rotate through the above-described loop, the motor M is driven at a constant speed (300 r.p.m.).

During the constant speed drive of 300 r.p.m., as the motor M rotates, the magnet 17a causes the first
When the needle up detection signal NLUP is detected, the program executes a routine 55 that presets a predetermined time in a timer counter in the microcomputer.
, a check routine 56 for determining the presence or absence of a rising signal of the needle up detection signal rising from the L level to the H level, a routine 57 for canceling the rotational speed of the motor M of 300 r.p.m., and the thread trimming. A routine 58 is reached in which the thread trimming solenoid that had been operating the mechanism is released, and the magnet 17a rotates past the sensor 13 for detecting the needle top position, and then the magnet 17b rotates and passes the second needle. The check routine 59 determines whether there is a falling signal of the upper detection signal NLUP from the H level to the L level, and the routine 60 applies reverse phase braking to stop the motor M, and the reverse phase braking is applied to the motor M. .

In this way, when the reverse phase braking is applied to the motor M, the program reaches the routine 62 from the check routine 61 for determining whether the timer counter has timed up, to the routine 62 for canceling the reverse phase braking, and the motor M
stops the needle 15 at the needle-up position and reaches address D.

Therefore, when stopping the sewing machine with the needle up, as shown in FIG.
A falling signal from the L level to the L level is detected, the timer counter is operated for a predetermined time T4, and a rising signal from the L level to the H level of the first detection signal NLUP is detected to select the speed command voltage C300. It outputs a selection control signal SG1 for canceling the above, and then detects a falling signal of the second needle-up detection signal NLUP from the H level to the L level, and sends the motor drive current supply circuit 34 to apply reverse phase braking to the motor M. Since the control signal SG3 is output to apply reverse phase braking until the timer counter times out, the pulse width of the detection signal NLUP may change due to temperature rise in the needle top position detection sensor 13. Even if the braking time T5 becomes smaller, the braking time T5 remains constant, and even if the response of the sensor 13 changes, the motor M can always be stopped at the needle-up position.

That is, as shown by the chain line in FIG. 10, the temperature of the sensor 13 rises, and the detection signal NLUP
Even if the falling time T6 becomes shorter, the braking time T5 remains constant because the timer counter operation start and the braking start are delayed by the same amount of time.

When the sewing machine completes the needle-up stop, the program passes through a routine 63 that drives and controls the wiper mechanism from address D, and then returns to a sewing routine 40 that controls the rotation of the motor M during sewing in response to the depression of the pedal PD. .

Note that the present invention is not limited to the above-mentioned embodiments, and may be applied to a fixed position stopping device for a motor used in other processing machines, or to (needle down position detection sensor 7), the needle can be stopped at a fixed position based on the respective rising or falling signals of the two needle down detection signals NLDN generated from the sensor, or vice versa. 1 object to be detected, 2 sensors, 2 needle down detection signals
It is also possible to make appropriate changes without departing from the spirit of the invention, such as by generating NLDN.

Effects As detailed above, according to the present invention, it is possible to eliminate variations in stopping at a predetermined rotational position due to fluctuations in the rotational speed of the motor, and to control the motor to stop at a predetermined rotational position at all times.

[Brief explanation of the drawing]

Fig. 1 is a front view of a sewing machine embodying the present invention, Fig. 2 is a sectional side view of main parts showing how the motor is installed, Fig. 3 is a sectional view taken along line A-A in Fig. 2, and Fig. 4 is An explanatory diagram showing the pedal depression area, Figure 5 is an electric block circuit diagram for motor drive control, Figure 6 is a flowchart of a program to drive and control the sewing machine, and Figures 7 and 8 are needle lowering. Time chart when the needle is stopped. Figures 9 and 10 are time charts when the needle is stopped. Figure 11 is the motor rotation speed curve when there is no tacking stitch. Figure 12 is the motor rotation speed curve when the tacking stitch is being used. It is. Sewing machine body 2, pulley 4, sewing machine main shaft 5, needle down position detection sensor 7, magnet 14, speed command voltage generation circuit 31, selector circuit 32, speed control circuit 33, motor drive current supply circuit 34, speed voltage detection circuit 35 , sewing machine operating position detection circuit 36, tacking and stitch count setting circuit 37, control circuit 38, motor M, pedal PD.

Claims (1)

[Claims] 1. One motor, a first current supply circuit that supplies a drive current in one direction to drive the motor, and a first current supply circuit that supplies a current in the opposite direction to stop the motor. a second current supply circuit that is disposed between the motor rotation shaft and the frame, and sequentially generates first and second position detection signals according to the rotational angular position of the rotation shaft during one rotation of the rotation shaft; a position detection device; a timer means for starting time measurement based on a first position detection signal from the position detection device and generating an end signal after a predetermined time; and the first and second position detection signals. Alternatively, the first current supply circuit is disabled based on a signal issued between them, and the second current supply circuit is enabled based on a second position detection signal, and the timer circuit is terminated. A fixed position stopping device for a motor, characterized in that a control means for disabling the second current supply circuit based on a signal is provided, and the control circuit is operated based on a motor stop command signal. 2. The motor according to claim 1, wherein the first and second position detection signals are rising and falling parts of one electric pulse generated from the position detection device. Fixed position stop device. 3. The position detection device consists of two detected objects placed apart from each other on one side of the rotating shaft of the motor and the frame, and one detector provided on the other side. 2. The motor determining method according to claim 1, wherein the first and second position detection signals are a rising portion or a falling portion of two electric pulses generated from the motor. Position stop device. 4. The position detection device consists of one detected object provided on either side of the rotating shaft of the motor and the frame, and two detectors arranged apart from each other on the other side. The fixed position stop of the motor according to claim 1, characterized in that the rising portion or falling portion of each electric pulse generated from the detector is used as the first and second position detection signals. Device.