JPS5943197B2 - Electric sewing machine safety device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric sewing machine, and more particularly to a safety device for the sewing machine.

The prior art will be explained with reference to the electromagnetic clutch type shown in FIGS. 1 to 3.

FIG. 1 shows the overall configuration of an electric sewing machine.

The main body MA of the sewing machine is placed on a table TA, and the lower side thereof is an oil tank OB containing lubricant for the sewing machine.

A pulley PUL2 and a position detection mechanism PS are attached to the sewing machine shaft, and the boolean IJ-PUL2 is driven by the pulley PUL1 via a belt VB.

The pulley PUL1 is connected to a transmission mechanism TP that includes a clutch and a brake section, and CB, which is driven by a motor MO, is a control section, and commands are given by the operation of a foot switch FSW.

In the transmission mechanism TP section, as shown in FIG. 2, a latch plate CLB is disposed between a clutch friction plate CLM and a brake friction plate BRM so as to be movable in the axial direction. PLUI is directly connected.

The clutch plate CLB rotates with respect to the clutch friction plate CLM by energizing the clutch coil CL, and stops rotating with respect to the brake friction plate BRM by energizing the brake coil BR.

Clutch coil CL is controlled by transistor T1 as shown in FIG. 3, and transistor T1 is operated by clutch signal CLS.

Similarly, the brake coil BR is also controlled by the transistor T3, which is operated by the brake signal BR8.

TR is a thread trimming drive coil, which is controlled by a transistor T2, which is operated by a thread trimming signal TR8.

Now, when the foot switch FSW shown in Fig. 1 is pressed forward, the clutch signal CLS is output and the clutch coil CL is energized and the second
Since the clutch plate CLB shown in the figure is attached to the clutch friction plate CLM and the boot IJ-PULI is rotated, the sewing machine shaft is rotated via the belt.

When you take your foot off the foot switch FSW from this state, it becomes a neutral state, and the position detection mechanism PS shown in Figure 1 detects the lower position of the sewing machine needle, sets the clutch signal CLS to zero, and outputs the brake signal BR8 for a short period of time. , brake coil BR
is excited and the sewing machine stops at the lower position.

Next, when the foot switch FSW is turned on, the thread trimming signal TR
8 and the clutch signal CLS are output simultaneously, the thread trimming drive coil TR and the clutch coil CL are excited, and the sewing machine shaft rotates and at the same time performs an automatic thread trimming operation.

When the sewing machine needle reaches the upper position, the position detection mechanism PS generates an upper position signal, simultaneously cuts the thread trimming signal TR8 and clutch signal CLS, generates the brake signal BR8 for a short time, and excites the brake coil BR to start the sewing machine. Stop in the upper position.

As mentioned above, this sewing machine can perform automatic thread trimming and upper and lower stop stitches.

However, the sewing machine MA is often tilted down for adjustment, and when the foot switch FSW is set to the road while the sewing machine MA is tilted down, the thread trimming signal TR8 and clutch signal CLS are input at the same time, and the thread trimming drive coil TR and clutch coil CL are input simultaneously. Excite.

However, if the sewing machine is tipped over, the belt VB connecting IJ-PULI and PUL2 is loose, and the sewing machine shaft is not driven, so the position detection mechanism PS does not generate an upper position signal and the clutch coil CL and thread trimmer The drive coil TR remains excited.

Normally, the thread trimming drive coil TR is used only for a very short time, so if it is energized for a long time, the coil TR will overheat and burn out.

Furthermore, as described above, it is very dangerous to return the machine to its original position while the coils are still energized and to cut the thread at the same time.

As mentioned above, conventional automatic sewing machines of the belt transmission type are extremely dangerous if the sewing machine is tipped over for adjustment and this happens after adjustment.

Furthermore, if the thread trimming drive coil was left open for a long time, there were frequent accidents in which the thread trimming drive coil was burnt out.

An object of the present invention is to provide a safe sewing machine that prevents burnout of a thread trimming drive coil even if the sewing machine is tilted down and a foot switch is stepped on during adjustment, and at the same time prohibits the thread trimming operation at the moment the sewing machine is raised.

The present invention provides clutch signal CLS and thread trimming signal TR8 when the gap between signals from position detection mechanism PS of the sewing machine becomes less than a certain reference value while clutch signal CLS is on.
At the same time, the brake coil BR is excited for a short time to stop the power transmission pulley PUL1, thereby ensuring safety when the sewing machine is tipped over for adjustment and preventing burnout of the thread trimming drive coil TR. It is something.

An embodiment of the present invention will be described with reference to FIGS. 4 and 5.

A position detection mechanism PS is directly connected to the sewing machine shaft boo IJ-PUL2, and this sewing machine shaft boo IJ-PUL2 is a transmission boo attached to the power transmission mechanism TP. J-PU
It is connected to L via a belt VB.

The power transmission mechanism TP is integrated with the motor MO, and an oil tank OB containing lubricating oil for the sewing machine is provided at the bottom of the sewing machine main body MA.

Further, the sewing machine main body MA can be laid down on the table TA to allow adjustment of the inside of the sewing machine.

CB is a control box, and a control circuit in the control box operates in response to a command from a foot switch FSW.

When the foot switch FSW is stepped forward, the front switch is turned on.
When you hit the road, the road switch will turn on.

When you release your foot again, it returns to neutral. Furthermore, the power transmission mechanism TP
will be explained using FIG.

A transmission pulley PUL1 is installed between the clutch friction plate CLM directly connected to the motor MO and the fixed brake friction plate BRM.
A clutch plate CLB directly connected to is arranged.

A clutch coil CL is disposed near the clutch friction plate CLM, and when this clutch coil CL is energized, the clutch plate CLB rotates about the clutch friction plate CLM, so power is transmitted to the bell IJ-PULI and the bell 1- Drive the sewing machine shaft through VB.

A brake coil BR is arranged near the brake friction plate BRM, and when this brake coil BR is energized, the clutch plate CLB applies a brake on the brake friction plate BRM, and the pulley PUL 1, belt vB1 boo IJ-PUL 2 to stop the sewing machine shaft.

Figure 4 shows the parts that constitute the safety device.

The collector of the transistor T1 is connected to one end of the clutch coil CL, and the other end of the clutch coil CL is connected to the positive terminal +■ of the power supply.

The base of the transistor T1 is connected to the clutch signal terminal CLS and the collector of the transistor T4 through a resistor R1.

The thread cutting and driving coil TR has one end connected to the collector of the transistor T2 and the other end connected to the power supply +V.

The base of the transistor T2 is connected to the thread trimming signal terminal TR8 and the collector of the transistor T through a resistor R2.

The brake coil BR has one end connected to the power supply +V and the other end connected to the collector of the transistor T3.

The base of transistor T3 is diode D2 and resistor B7.
It is connected to the brake signal end BR8 through the diode D1 and to the output terminal Q of the monostable multi-MM2 through the diode D1.

The emitters of the transistors T1 to T are commonly connected to GND on the negative side of the power source.

DD is a signal terminal of a device for detecting the lower position of the sewing machine needle, and is connected to input A of the monostable multi MM1.

The output terminal Q of the monostable multi MM1 is applied to the capacitor C and the positive input of the comparator COM through a resistor R4.

A reference voltage STS is applied to the negative input of the comparator COM.

Capacitor C and reference voltage! The other end of EfSTS is connected to the negative electrode side of the power supply.

The output of the comparator COM is connected to the input 1 of the AND circuit AND, and the input 2 is connected to the clutch signal end CLS.

The output of the AND circuit AND is connected to the set terminal S of the flip-flop FF.

The reset terminal R is connected to the front contact of the foot switch FSW, and the output terminal Q is connected to the transistor T4. It is connected to the base of T5 and the B terminal of monostable multi-MM2.

The clutch signal CLS, brake signal BR8, thread trimming signal TR8, and front contact point of the foot switch FS'W shown in FIG. 4 are provided by a circuit as shown in FIG.

The front contact of the foot switch FSW is connected to the resistor R8, the reset terminal R of the flip-flop FF1, and the NOR circuit NOR1.
It is connected to the input 1 of the OR circuit OR1 and the input 2 of the OR circuit OR1.

The neutral contact N is connected to the resistor R0 and the input 2 of the AND circuit AND1, and the road contact T is connected to the resistor R1o and the set terminal S of the flip-flops FF1 and FF2.

The other ends of the resistors R8 to R7° are connected to the negative pole side of the power source, and the movable piece of the foot switch FSW is connected to the positive pole side of the power source.

DD is a lower position signal that generates an L (LOW) level signal when the needle of the sewing machine is in the lower position, and is connected to input 1 of the AND circuit AND.

UD outputs an L level signal when the needle of the sewing machine is in the upper position, and generates an H (HIGH) level signal in other positions, which is passed through the logic inverter INV to the reset terminal R of the flip-flop FF2 and the logic AND circuit A.
It is connected to input 2 of ND2.

Thread trimming signal TR8 from output Q of flip-flop FF2
occurs.

The output Q of the flip-flop FF1 is an AND circuit AND2
Q is the input 1 of the logic NOR circuit N0R2.
The output of the AND circuit AND2 is connected to the NOR input 2 of the NOR circuit and the input 3 of the OR circuit OR1.

The output of the AND circuit AND1 is connected to the input 1 of the OR circuit OR1 and the input 2 of the NOR circuit N0R1.

The output of the NOR circuit NOR1 and the output of the NOR circuit N0R2 are input to the inputs 1 and 2 of the logic OR circuit OR2.
The output of R2 is connected to the input terminal B of the monostable multi-MM.

The clutch signal CLS is obtained from the output of the OR circuit OR□, and the brake signal BR8 is obtained from the output Q of the monostable multi-MM.

If we now press the foot switch FSW, the power supply voltage ■ will be applied to the front contact as shown in Figure 5, and it will go to H level.
Since the input 2 of the OR circuit OR1 goes to H level, the output also goes to H level.
As a result, a signal is generated at CLS, which conducts transistor T1 and excites clutch coil CL, so that clutch plate CLB in Fig. 2 is attracted to clutch friction plate CLM and drives the sewing machine through pulley PULI, belt VB, and pulley PUL2. .

Further, the input 1 of the NOR circuit N0R1 becomes H level, and the output becomes L level.

The reset R of flip-flop FF1 enters H level, and the input 1 of NOR circuit N0R2 also becomes H level, and the output becomes L level, so the output of OR circuit OR2 also becomes L level, and the brake signal BR8 is not output. .

In this state, input 2 of the AND circuit AND in FIG. 4 is at H level, but since the sewing machine is operating, the lower position signal D
D occurs continuously, the duty of Q is small, and the comparator COMQ) smoothed by the resistor R4 and capacitor C is smaller than the reference value STS, so the output of the comparator COM is at L level.

It is acid and circuit AND. The output also goes to the L level, and since no signal enters the setting manual S of the flip-flop FF, the output Q also goes to the L level, and the transistors T4. T...
Monostable multi-MM2 does not work.

Next, when the foot switch FSW is returned to neutral, the OR circuit OR1
The input 2 of the AND circuit AND becomes an L level, but until the input 2 of the AND circuit AND becomes an H level and the lower position signal arrives, the input is at an H level, so the H level enters the input 1 of the OR circuit OR1, and the output is also The clutch signal CLS is at H level and is output.

When the sewing machine shaft rotates and the lower position of the sewing machine needle is detected and the signal of DD goes to L level, the output of AND circuit AND1 also goes to L level and clutch signal CLS disappears, and at the same time inputs 1 and 2 of NOR circuit N0R1 go to L level. , the level becomes,
The output becomes H level, the output of the OR circuit OR2 is set to H level, and the monostable multi MM is struck, and the output Q is set to H level for a certain period of time and the brake signal BR8 is given, so the clutch is disengaged and the brake is applied at the same time, and the sewing machine starts. Stops in the lower position.

Next, when the foot switch FSW is pressed to the road, the road contact T becomes H.
level, a signal enters the set terminals S of flip-flops FF1 and FF2, and in order to set the output Q to the H level, a thread trimming signal TR8 is generated.

In addition, the input 1 of the AND circuit AND2 also becomes H level, and since the upper position signal UD is at H level until the upper position is reached, the input 2 of the AND circuit AND2 also becomes H level, and the output is set to H level and the input 3 of the OR circuit OR1 is set to H level. level and apply the clutch signal CLS.

Therefore, the sewing machine rotates to trim the thread and reaches the upper position, and when the upper position signal UD goes to L level, the reset terminal R of flip-flop FF2 goes to H level and its output goes to L level.
level, and the thread trimming signal TR8 disappears.

At the same time, the input 2 of the AND circuit AND2 also goes to the L level, and the output also goes to the L level, so the output of the OR circuit OR1 also goes to the L level, and the clutch signal CLS also disappears.

Furthermore, the Q of flip-flop FF1 is L level,
Since the surface input of NOR circuit N0R2 is L level, OR circuit O
Input 2 of R2 becomes H level, a signal enters the monostable multi-MM, a signal for a certain time is generated at output Q, and the brake is applied to stop the sewing machine at the upper position.

As described above, when the sewing machine is operating normally, the lower position signal DD is input continuously, so the output Q of the monostable multi-MM1 also repeats H level and L level, and within the period of H level, the capacitor C and the resistor The voltage integrated by R4 is the reference signal S
The capacitor C is smaller than the voltage of TS and during the L level period.
is discharged through the resistor R4, so the output of the comparator COM is always at the L level.

Therefore, the output of the AND circuit AND is always at L level,
Since flip-flop FF does not operate and its output Q does not go to H level, transistors T, , T and monostable multi MM2 also do not operate, so clutch signal C
It has no effect on LS, thread trimming signal TR8, brake, etc.

Next, consider what happens when the sewing machine is knocked over.

Using a sewing machine as an example, when you step forward on the foot switch FSW, the clutch signal CLS is output as described above, so the boot IJPUL2 directly connected to the clutch plate CLB rotates, but the belt VB is loose and the sewing machine shaft is not rotating. , the lower position signal DD is also not generated.

Therefore, the output Q of the monostable multi MM1 remains at H level, and the voltage of the comparator COMQ) increases by the time constant of the resistor R4 and the capacitor, becomes higher than the reference signal voltage STS, and the output becomes H level.

Since the clutch signal CLS is also at H level, the AND circuit AND
The output of T4 and T5 also becomes H level, and the set terminal S of flip-flop FF also becomes H level, so the output also becomes H level, transistors T4 and T5 become conductive, and transistors T1 and T5 become conductive. T
Since the pace emitters of 2 are short-circuited, the clutch coil C
At the same time as the L current is cut off, a signal is applied to the input B of the monostable multi-MM2, and the output Q is set at the H level for a certain period of time to excite the brake coil BR and stop the sewing machine.

Also, when the foot switch FSW is set to the road with the sewing machine tilted down, the flip-flop FF1 in FIG.
FF2 operates and clutch signal CLS and thread trimming signal TR
8 comes out.

However, since the belt VB is loose, the sewing machine does not rotate and the lower position signal DD shown in FIG. level and sets the flip-flop FF to bring the output Q to the H level, making the transistors T, , T5 conductive, so the clutch signal CLS
and the thread trimming signal TR8 are short-circuited to cut off the currents of the clutch coil CL and the thread trimming drive coil TR. At the same time, the monostable multi-MM2 is operated to keep the output Q at H level for a certain period of time, and the brake signal BR8 is generated to start the sewing machine. make it stop.

Therefore, even if this state continues, the thread trimming drive coil TR will not be burnt out and the thread trimming operation will not occur, so it is safe.

By changing the integral time constant by changing the values of the resistor R4 and the capacitor C, the signal of the comparator COM becomes H level after the sewing machine is turned over and the foot switch FSW is operated, and the clutch CL and thread trimmer are activated. It is possible to adjust the time until the drive coil TR becomes invalid, and the time can be freely selected.

Further, the rotational speed of the sewing machine shaft at which the safety circuit shown in FIG. 4 operates can be freely adjusted by changing the values of resistor R4 and capacitor C or by changing the reference signal STS.

Also, even if you raise the sewing machine from this state, it will not operate, and in order to make it work normally, press the front foot once after raising it and reset the flip-flop FF as shown in Figure 4. returns to normal operation.

As described above, the present invention can prevent burnout of the thread trimming drive coil due to erroneous operation when using a sewing machine as an example, and can provide a safe sewing machine by disabling the thread trimming operation.

Although FIG. 4 of the above embodiment compares the pulse interval of the lower position signal DD with the reference signal STS, the same effect can be obtained by using the upper position signal UD of the Mimin needle shown in FIG.

Similar effects can also be obtained by using a signal proportional to the rotational speed of the sewing machine shaft, such as a finger speed generator attached to the sewing machine shaft.

Furthermore, the belt V obtained is in the same state as when the sewing machine was turned over.
Even when B is cut, the pulley is loosened, the sewing machine shaft is locked, etc., the sewing machine operates in the same manner as in the embodiment described above, and is effective as a safety measure.

In the present invention, when the rotation signal of the sewing machine shaft becomes lower than the reference signal, a stop signal is generated and the clutch signal and thread trimming signal are disabled. It is extremely safe because the sewing machine does not operate, and even if the sewing machine is turned over and raised after operating the foot switch, the sewing machine will not suddenly start operating.

Further, even if the sewing machine is turned over and the foot switch is turned on to energize the thread trimming drive coil, the current in the thread trimming drive coil is cut off after a time constant determined by the resistor and capacitor has elapsed, thereby preventing the coil from burning out.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing the configuration of an electric sewing machine, and Figure 2 is an explanatory diagram showing the configuration of an electric sewing machine.
3 is an electrical connection diagram showing the drive unit of a conventional example, FIG. 4 is an electrical connection diagram of the drive unit showing an embodiment of the present invention, and FIG. 5 is an electric sewing machine. FIG. 3 is an electrical connection diagram showing an embodiment of the signal section of FIG. Explanation of codes, MA...Bessin body, PS...
...Position detection mechanism, PULI...Transmission pulley,
PUL 2... Sewing machine shaft pulley, VB...
...Belt, OB...Oil tank, TA...
・Bassin table, TP...Power transmission mechanism, M
O: Motor, L: Front contact of foot switch, N: Neutral contact of foot switch, T
・・・・・・Road contact of foot switch, N0R1...
...Logic NOR circuit, N0R2...Sick NOR circuit, OR1...Logic OR circuit, OR
2...Logic OR circuit, INV...
Logic impark circuit, +V...DC voltage,
UD...Upstream position signal.

Claims (1)

[Claims] 1.Equipped with a mechanism that drives the sewing machine by a motor, a mechanism that stops the sewing machine shaft with a brake, and a mechanism that detects the rotation of the sewing machine shaft, and the mechanism that detects the rotation of the sewing machine shaft detects that the rotation of the sewing machine shaft is below the reference rotation speed. 1. A safety device for an electric sewing machine, characterized in that when it is detected that the sewing machine drive mechanism is disabled, the brake coil of the brake mechanism is energized for a short time to stop the sewing machine drive shaft.