JPS5934392B2 - 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 a 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 lubricated oil for the sewing machine.

Pulley PUL2 and position detection mechanism PS are attached to the sewing machine shaft, and Boo! J-PUL2 is driven by pulley PUL1 via belt VB.

The pulley PULI is driven by the motor MO through a transmission mechanism TP including a clutch and a brake section.

CB is a control unit to which commands are given by the operation of a foot switch FSW.

As shown in FIG. 2, the transmission mechanism TP section includes a latch plate CLB that is movable in the axial direction and is disposed between a clutch friction plate CLM and a brake friction plate BRM, and the pulley PUL1 is directly connected to this clutch plate CLB. has been done.

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.

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
Attach the clutch plate CLB shown in the figure to the clutch friction plate CLM and boom! Since J-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 passed, the clutch signal C
LS and 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, turns off the clutch signal CLS, generates a brake signal BR8 for a short time, and excites the brake coil BR to stop the sewing machine at the upper position.

This sewing machine can stop stitches up and down as described above.

In this device, the driving of the sewing machine shaft is stopped by the axial movement of the clutch plate CLB, but if this axial movement is not performed smoothly due to wear, foreign matter, etc., normal operation will not occur.

On the other hand, if the clutch plate CLB is biased toward the brake wear plate BRM and does not move in the axial direction as previously proposed by the inventors, the sewing machine shaft will not rotate and the safety device will operate, causing the clutch coil CL to Because the current is cut off,
Do not perform unsafe operations.

However, if the clutch plate CLB is biased towards the clutch wear plate CLM and does not move in the axial direction, the above safety circuit will not operate, and even if the current in the clutch coil CL is cut off, the clutch plate CLB and the clutch friction plate CLM will not move. Due to the mechanical connection, the sewing machine shaft rotates and performs extremely unsafe movements.

An object of the present invention is to stop the sewing machine shaft and simultaneously issue an alarm when such an unsafe operation occurs.

In Fig. 3, if the sewing machine shaft rotates when the clutch signal CLS is not output, if a current is applied to the brake coil BR to stop the sewing machine, the above purpose is achieved, but Boo! Even when JPUL2 is operated by hand, current flows through the brake coil BR and the brake is activated, causing the sewing machine to stop, making manual operation of the pulley impossible.

However, when the pulley is operated manually, it is necessary to prevent the brake from working.

FIG. 4 shows an example of the circuit of the present invention.

The collector of the transistor T1 is connected to one end of the clutch coil CL, and the other end of the clutch coil is connected to the positive pole V of the power source.

The base of transistor T1 is connected to clutch signal terminal CLB through resistor R1.

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 the transistor T3 is connected to the brake signal BH3 through a diode D2 and a resistor R3 and to the output terminal Q of the monostable multi-MM2 through a diode D1.

Transistor T1. The emitters of T3 are commonly connected to GND on the negative side of the power supply.

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 monostable MM1 is applied through resistor R4 to capacitor C and the positive input of comparator COM.

The other end of the capacitor C and the reference voltage STS is the negative terminal G of the power supply.
Connected to ND.

The output of the comparator COM is connected to the input 1 of the NOR circuit NOH, and the input 2 is a monostable multi MM3 which receives the signal of the clutch signal terminal CLS and is sent the signal of the clutch signal terminal CLS for a certain period of time. The output Q of is connected.

The output of the NOR circuit NOH 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 FSWO, and the output terminal Q is connected to the base of the transistor T4 and the B terminal of the monostable multi-channel MM2 through a resistor R3.

The emitter of the transistor T4 is connected to the negative side GND of the power supply, and the collector is connected to one end of the coil W of the alarm.

The other end of the alarm coil W is connected to the power supply +V.

The clutch signal CLS, brake signal BR8, and front contact point of the foot switch PSW 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, the input 1 of the NOR circuit N0R1, and the input 2 of the OR circuit OR1.

The neutral contact N is the resistor R0 and the input 2 of the AND circuit AND1, and the road contact T is the resistor R1o and the flip-flops FFI and F.
It is connected to the set terminal S of F2.

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

DD is a lower 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, generates an H (HIGH) level signal at other positions, and is connected to input 2 of the logic AND circuit AND2.

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 ANDi is connected to the input 1 of the OR circuit ORI and the input 2 of the NOR circuit N0R1.

The output of the NOR circuit N0R1 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 2 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 OR1, and the brake signal BR8 is obtained from the output Q of the monostable multi-MM.

If we now press the foot switch FSW, a power supply voltage of 10 V will be applied to the front contact in Fig. 5, and it will become 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, conducts the transistor T2, and excites the clutch coil CL, so that the crack plate CLB shown in Fig. 2 is attracted to the clutch friction plate CLM side, and BOOM!
Drive the sewing machine through J-PUL, bell 1-VB, and pulley PUL2.

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

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

In this state, the input 2 of the NOR circuit in Figure 4 is at H level, so the output of the NOR circuit is at L level, and since no signal enters the set input S of the flop FF, the output Q is also at L level.
level, and the transistor T monostable multi MM2 does not operate.

Next, when the foot switch FSW is returned to neutral, the OR circuit ORI
The input 2 of the AND circuit AND1 goes to the L level, but the input 1 of the AND circuit AND1 goes to the H level until the lower position signal DD arrives, and the output also goes to the H level and the clutch signal CLS 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 N0RI go to L level. Then, the output becomes H level, the output of OR circuit OR2 is set to H level, the monostable multi MM is hit, the output Q is set to H level for a certain period of time, and brake signal BR8 is given, so the clutch is disengaged and at the same time the brake is applied and the sewing machine is Stops in the lower position.

Input 2 of the NOR circuit NOH in Fig. 4 is at L level, and since the lower position signal DD is continuously output during rotation, the output Q of monostable multi-MM1 is at L level, and capacitor C has a photovoltaic voltage. Therefore, the input voltage of the comparator COM is lower than that of the input terminal, and the output of the comparator COM is at L level.

At the same time as the clutch signals CL and S disappear, a signal enters the monostable multi-MM3 and its output Q is the clutch signal CLS.
Since the input 2 of the NOR circuit NOH is held at the H level for a certain period of time after the current has disappeared, the input 2 of the NOR circuit NOH is held at the H level for a certain period of time.

In the meantime, the capacitor C completes charging and the input voltage of the comparator COM becomes higher than the one input terminal, and the input 1 of the NOR circuit NOH becomes H level, so the output of the NOR circuit NOH becomes L.
remains at the level.

If the clutch plate CLB remains in contact with the clutch friction plate CLM even though the current in the clutch coil CL is cut off, and therefore the sewing machine stops once and then starts rotating again, the output Q of the monostable MM3 will be Even after it becomes L level, the lower position signal DD continues to be output, and the monostable multi-MM1 works, and the capacitor C cannot be charged, so the comparator COM
Since the output of the NOR circuit becomes L level, both inputs 1 and 2 of the NOR circuit become L level, and the output of the NOR circuit becomes H level.

Therefore, a signal enters the set terminal S of the flip-flop FF, and the output Q becomes H level, so the transistor T4 becomes conductive, current flows through the alarm coil W, and a relay signal is issued.At the same time, an input signal is input to the monostable multi-MM2. The output Q becomes H level for a certain period of time and the transistor T3
becomes conductive and stops the sewing machine.

When the pulley is manually moved after the down stop, the down position signal DD is output, but the time is long because it is a manual operation.

Therefore, if you set the reference voltage STS so that the output of the comparator COM does not go to L level during manual operation, you can apply the brakes to stop it if it rotates at an unsafe speed faster than a person can rotate it by hand. It becomes possible to operate an alarm device (buzzer, etc.) at the same time.

As described above, according to the present invention, if the clutch coil CL is disconnected and the sewing machine turns faster than a person can turn it by hand, the brakes are automatically applied and an alarm can be issued, which greatly improves safety. There is.

Although the lower position signal DD is used in the embodiment, the present invention is not limited to this, and it is equally possible to use a signal related to the rotation of the sewing machine, such as an upper position signal UD.

Further, in this embodiment, the monostable multi-MM2 is used in FIG. 4 to enable the brake for a short time, but it is also possible to enable the brake continuously.

[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 a drive section of a conventional example, FIG. 4 is an electrical connection diagram of 1 drive section showing an embodiment of the present invention, and FIG. FIG. 2 is an electrical connection diagram showing an embodiment of a signal section of the sewing machine. MA...Sewing machine body, PS...Position detection mechanism, PUL...Transmission pulley, PUL2.
...Shinshaft pulley, VB...Belt, O
B...Oil tank, TA...Sewing machine table, TP...Power transmission mechanism, MO...
・Motor, L...Front contact of foot switch, N
・・・・・・Neutral contact of foot switch, T・・・・・・
Road contact of foot switch, N0R1...Logic NOR circuit, N0R2...Logic NOR circuit,
OR1...Logic OR circuit, OR2...
・Logic OR circuit, 10■・・・DC voltage, U
D...Top position signal.

Claims (1)

[Claims] 1. A mechanism that drives a sewing machine using a motor, a mechanism that stops the sewing machine shaft using a brake, and a mechanism that detects the rotation of the sewing machine shaft, and when there is no rotation command and the speed of the sewing machine shaft is equal to or higher than a reference value. 1. A safety device for an electric sewing machine, characterized in that the safety device detects that the brake mechanism is on the brake mechanism and stops the sewing machine shaft. 2. A safety device for an electric sewing machine as set forth in claim 1, characterized in that it issues an alarm at the same time as stopping the sewing machine shaft.