WO1983001967A1

WO1983001967A1 - Motor-driven sewing machine

Info

Publication number: WO1983001967A1
Application number: PCT/JP1982/000453
Authority: WO
Inventors: Denki Kabushiki Kaisha Mitsubishi
Original assignee: KUMATANI, Hiroshi;
Priority date: 1981-11-30
Filing date: 1982-11-29
Publication date: 1983-06-09
Also published as: KR860000399B1; GB2135345B; DE3249227T1; GB8320138D0; GB2135345A; KR840002477A

Abstract

Motor-driven sewing machine which rotatably drives a sewing shaft (11) by a motor (14) so as to drive a sewing needle (1) reciprocatingly. In a sewing machine having the sewing shaft (11) driving the needle (1), a sewing frame (10) rotatably journaling the shaft (11) and the motor (14) driving the shaft (11), the rotor (40) of the motor is mounted on the shaft (11) and the stator (38) of the motor is mounted in the frame (10). Thus, the parts such as a belt or pulleys which have previously been necessary to transmit power between the motor (14) and the shaft (11) at the side of the frame (10) can be omitted, the structure of the entire machine can be simplified and the cost of the machine can be reduced.

Description

Specification

Title of invention

electric sewing machine

Technical field

The present invention relates to an electric sewing machine, and more particularly to a sewing machine shaft for reciprocating a sewing needle, which is driven by an electric motor.

Background technology

In general, an electric sewing machine consists of a sewing machine mechanism section including a sewing machine upper shaft for reciprocating a sewing machine needle and a sewing machine frame supporting the shaft, and this sewing machine mechanism. It consists of a motor that drives the parts and a position detector that detects the position of the sewing machine needle. Rotational output obtained from the output shaft, which is directly connected to the shaft of the motor or via a clutch, is transmitted to the above-mentioned sewing machine via the motor pulley, transmission belt and sewing machine. given to the pin top axis. If the motor has a braking effect such as an induction motor, an electromagnetic brake is provided to control the rotational speed of the upper shaft of the sewing machine. Furthermore, a control means is provided for controlling the brake and the electric motor based on the detection output of the position detector, thereby stopping the sewing machine needle at a predetermined position. It has become so. The switch means also controls the motor and brake means via the control means. This switch means is, for example, a foot switch or the like. In the conventional sewing machine as described above, in any case, the sewing machine mechanism and the electric motor are constructed separately, and the electric motor consists of a motor frame and a motor stator. , the motor shaft and the motor rotor are independently formed, and are connected to the sewing machine mechanism through the above-mentioned two pulleys, belts, joints, or other connecting means. was completed. For this reason, in the conventional electric sewing machine of this kind, the parts for connection occupy a relatively large proportion of the constituent elements of the sewing machine. This has been a major impediment to miniaturization and cost reduction.

In addition, the separate configuration of the sewing machine mechanism and the electric motor itself is also necessary in order to simplify the configuration of the electric sewing machine, make it more compact, or reduce the cost. However, it could not be said to be rational.

Furthermore, this type of electric sewing machine requires position detection means for controlling the stop position of the sewing machine needle. Since it was attached to the joint between the machine and the sewing machine mechanism, the joint became even more complicated. - Invention disclosure

The present invention has been made in view of the above-mentioned problems of the prior art, and its object is to reduce parts such as brakes and belts or joints that are indispensable for the connection between the sewing machine mechanism and the electric motor. OMPI It is an object of the present invention to provide an electric sewing machine capable of greatly simplifying the configurations of the sewing machine mechanism and the electric motor and reducing the cost thereof. .

In order to achieve the above object, the present invention provides a sewing machine shaft for reciprocating a sewing machine needle, a frame for supporting the sewing machine shaft, and a mechanism for driving the sewing machine shaft. and a rotor of the motor is mounted on the sewing machine shaft, and a stator of the motor is mounted on the frame.

Brief description of the drawing

FIG. 1 is a conceptual diagram showing an electric sewing machine according to the present invention, FIG. 2 is an overall block diagram showing a preferred embodiment of the present invention, and FIG. 3 is a detailed view of the pedal detection circuit shown in FIG. Fig. 4 is an explanatory diagram showing the detailed construction of the sewing machine control circuit shown in Fig. 2; Fig. 5 is an explanatory diagram showing the detailed construction of the low speed detection circuit shown in Fig. 4; Fig. 6 is an explanatory diagram showing the waveforms of each part of the low speed detection circuit in Fig. 5, Fig. 7 is an explanatory diagram showing the details of the motor speed control circuit shown in Fig. 2, Fig. 8 is a Fig. 9 is a diagram showing the overall configuration of another preferred embodiment of the present invention; Fig. 10 is a diagram of the motor speed control circuit; FIG. 4 is an explanatory diagram showing details;

Best Mode for Carrying Out the Invention

Prior to the description of the embodiments of the present invention, the electric power of the present invention will first be described. The overall configuration of the dynamic sewing machine will be briefly explained.

FIG. 1 is a conceptual diagram showing the whole electric sewing machine according to the present invention. The electric sewing machine shown in FIG. and an induction motor 14, and a position detector 24 as position detection means for detecting the position of the sewing machine needle, and a brake means as brake means. It has an electromagnetic brake 18. Here, the motor 14 does not have an independent motor frame, and therefore the motor stator is attached to the sewing machine frame 10 of the sewing machine mechanism. On the other hand, the rotor 40 of the electric motor 14 and the position detector 24 are mounted directly on the sewing machine upper shaft 11 on the sewing machine mechanism side. Therefore, the motor 14 does not have an independent motor shaft, and the upper shaft 11 also serves as the motor shaft. Similarly, a sewing machine frame 10 on the sewing machine mechanism side constitutes a motor frame. In this way, the motor ^I4 and the position detector 24 are mounted on the sewing machine upper shaft 11, respectively. Furthermore, an electromagnetic brake 18 is also mounted on the upper shaft 11 of the sewing machine. As a result, parts such as pulleys and transmission belts for connecting the motor 14 and the sewing machine mechanism are almost unnecessary. is greatly simplified, and its cost is greatly reduced. Furthermore, the moving nucleus 14 itself is also greatly simplified compared to the conventional independent configuration. devil In addition, since the position detector 24, the electromagnetic brake 18, etc., are all assembled on the upper shaft 11 of the sewing machine]), the number of parts and labor required for mounting them are greatly reduced. is saved to And this will make it possible to further reduce the size and manufacturing cost. ¾ 12 indicates control means and 28 indicates switch means.

2 to ⁸ , 10 is a sewing machine frame, 14 is a sewing machine upper shaft.

11 is an AC induction motor, 24 is a position detector attached to the sewing machine upper shaft 11]), 38 is a stator, 40 is a rotor, and the above configuration are identical to those already described for FIG.

The sewing machine upper shaft 11 is configured to perform variable speed operation and fixed position stop via the motor 14 by a motor speed control circuit 32 including a variable voltage/frequency inverter circuit. ^ru.

An example of a switch means, pedal sensing circuit 30 coupled to foot pedal 28, is shown in detail in FIG.

, The configuration will be explained below.

In FIG. 3, the detection circuit 30 consists of photointerrupters 42 and 44, a shielding plate 46 which moves through the gap between these photointerrupters, and a resistor ^48. sensor unit ⁵⁰ , magnet 52 cooperating with shield plate 4S, hall element 54 magnetically coupled with magnet 52 to generate speed command during sewing operation, resistor connected to hall element 54 ⁵⁶ , Speed command generated by Hall element 54 and a magnetic sensor unit ⁶⁰ consisting of an amplifier ⁵⁸ that amplifies the speed command signal VC and outputs it to the control circuit 32.

46 and magnet 52 are out of step with foot pedal 28 .

When the foot pedal 28 is stepped on, the degree of magnetic coupling between the magnet 52 and the Hall element 54 varies depending on the magnitude of the step.

As the value of the speed command signal VG changes and the shielding plate ⁴⁶ descends, the outputs of the photointerrupters 42 and 44 become "0" and "1", respectively, indicating that the sewing operation is in progress. It is sent to the control circuit 32 as the operation command signals St and _S2 representing this. Also, when the foot pedal 28 is in the neutral state as shown in _FIG . Further foot pedal 28

In the state of "return" _, that is, in the state of rotation in the opposite direction of the depression, the sewing thread is cut. ” and “0”, and the control circuit 32 discriminates that it is in the “Keep!) Return” state.

A needle up position signal ϋ P and a needle down position signal DN representing the position of the sewing machine needle 1 are output from the position detector 24, and the outputs of the position detector 24 and the pedal detection circuit 30 are respectively Electric motor

It is supplied to a sewing machine control circuit ³⁴ that controls the speed of W and various solenoids (not shown) of the sewing machine.

As shown in Fig _. 4, the sewing machine control circuit ³⁴ is provided with a fault signal storage circuit ( Hereinafter referred to as the FF circuit.

OMPI The positive output of circuit ^β2 is sent as a start signal SRT directly to speed control circuit 32 via OR circuit ⁶⁶ , and brake one-shot is performed. It is sent as a brake signal BK to the speed control circuit 32 via the circuit ⁶⁸ . That is, when the operation command signal becomes "1" and the affirmative output of the FF cycle ¾62 becomes "1", the speed control circuit 32 controls the drive of the sewing machine upper shaft 11 based on the speed command signal VC. Let's do it.

The positive output of the FF circuit 64 is directly sent to the speed control circuit 32 as a low speed speed command signal LLKD, and the OR circuit ⁶⁶ and the sewing machine control circuit ? supplied to 0. This FF circuit

⁶⁴ operates when the foot pedal 28 is in the "return" state, i.e., after the sewing machine stops, and when the sewing thread is cut]), and the speed command signal _S2 Say "1"! ¹ F Positive output of circuit ⁶⁴

When it becomes "1", the low speed command signal LLKD is first supplied to the speed control circuit 32 to raise the sewing machine needle 1, and then the sewing machine control circuit ⁷⁰ operates the solenoid for thread trimming. The sewing machine needle 1 finally stops at the upper position to control the thread wiper IS and the wiper WP for thread wiping. When the sewing machine needle is not in the up position, the up position signal UP is sent to the reset input of FF circuit 64 via NAND circuit 2 in order to stop the upper shaft 11 of the sewing machine at the up position. are supplied. At this time, the affirmative output of the FF circuit ⁶² is sent to the NAND circuit via the inverter 74 so as not to cause any trouble even if the foot pedal 28 is depressed by mistake. supplied to the other input of driver 2. The brake one-shot circuit 68 keeps the brake signal BK in the speed control circuit 32 for a predetermined time from when the positive outputs of the FF circuits 62 and 64 are respectively inverted from "1" to "0". to immediately stop the upper shaft 11 of the sewing machine.

O

The sewing machine control circuit 34 also has a low speed detection circuit ⁷⁶ to which the upper position detection signal UP and the lower position detection signal DN of the position detector 24 are supplied. This circuit detects that the rotation of the sewing machine 10 has reached a low speed according to the cycle of the lower speed detection signal DN, outputs a low speed detection signal LDN, and resets the FF circuit 62. The details are shown in Fig. 5. That is, the flip-flop ⁷⁸ to which the upper position detection signal UP and the lower position detection signal DN of the position detector 24 are supplied to the set terminal S and the reset terminal II, respectively, and its positive output A time constant circuit ⁸⁶ consisting of a fixed resistor SO connected to terminal Q, a variable resistor ⁸² , and a charging capacitor S4; One inverter ⁸⁸ and this inverter

⁸⁸ and a NOR circuit 90 to which the positive output of the flip-flop ⁷⁸ is fed. Also, 92 is a diode for rapid discharge of capacitor ⁸⁴ .

Accordingly, the positive output of the flip-flop 78 is "1" and "?" by the upper position detection signal UP and "1" by the lower position detection signal DN, as shown in FIG. ^6A . 0" and ]?, therefore the charging voltage of capacitor 84 is such that the ^positive output is " It gradually rises in the section of "1" and rapidly falls in the section of "0", and this state is repeated. When the rotation speed decreases, the charging voltage exceeds the reference set value, and at this point the output of the inverter 88 is reversed from "1" to "0" as shown in Fig. ^6c , and this Therefore, the low speed detection signal LDN indicating that the speed has reached the low speed is output from the NOR circuit ⁹⁰ , and the FF circuit 62 is reset.

Next, the motor speed control circuit 32 for driving the motor 14 to which each output of the sewing machine control circuit 34 and the speed command signal V C of the pedal detection circuit 30 are supplied will be described with reference to FIG.

That is, the command circuit ⁹² to which the speed command signal VC of the magnetic sensor unit ⁶⁰ of the pedal detection circuit 30 and the stop preparation command signal IMC0 and the low speed command signal LLK0 of the sewing machine control circuit ³⁴ are supplied. , a voltage control circuit ⁹⁴ and a frequency control circuit 9S to which the voltage and frequency command signals obtained from this command circuit ⁹² are respectively supplied, the outputs of these circuits 94 and 96 and the sewing machine control circuit 34 a transistor drive circuit to which the start signal SRT of the drive circuit 98 is supplied; a transistor inverter circuit 100 to which the output TD of the drive circuit ⁹⁸ is supplied; A rectifying circuit 102 for rectifying a three-phase AC power supply, a smoothing circuit 10 interposed between this rectifying circuit 102 and a transistor power circuit 100, the output of a command circuit 92 and - Brake circuit 106 to which brake signal BK of sewing machine control circuit 34 is supplied; 14 to drive the electric motor 14 and control the electromagnetic brake 18 by the output of the brake circuit 106 . In addition, the smoothing circuit 104 is provided with a protection circuit ¹⁰⁸ for detecting an abnormal current. be. Furthermore, the voltage control circuit 94 is connected to the output terminal of the inverter power circuit 100 via a transformer 101, and is stabilized by voltage feedback.

Thus, the voltage control circuit 94 and the frequency control circuit ⁹⁶ are controlled by the output of the command circuit ⁹² based on the start signal SRT of the sewing machine control circuit 34 and the respective speed ^command signals LLKO, IMCO and VC. The voltage and frequency are adjusted to keep the rotation speed of the electric motor 14 within a predetermined reference value, and the output of the brake circuit 106 excites the electromagnetic brake 18 to position the sewing machine needle. stop at the same position.

Next, the operation of the electric sewing machine with the above configuration will be explained.

O

When starting the sewing work, the foot pedal 28 is depressed to bring the magnet 52 closer to the Hall element 58, and the sewing speed command signal VC is sent from the magnetic sensor ⁶⁰ to the motor speed control circuit 32. At the same time, the photointerrupter 44 outputs an operation signal Si of "1" to the sewing machine control circuit 34. Following this, a start signal SRT of "1" is output from the sewing machine control circuit 34 to the speed control circuit 32, and a working output power is sent to the electric motor 14.

Cr.'.PI is issued and its driving is started. Then, in the speed control circuit 32, the commanded speed is converted by the voltage control circuit ⁹⁴ and the frequency control circuit ⁹⁶ into voltage and frequency corresponding to the commanded speed, and the motor 14 is rotated at a predetermined speed. The upper shaft 11 is rotationally driven.

When decelerating during sewing work, the foot pedal 28 can be returned. to rapidly decelerate and quickly stabilize at the required deceleration value.

During such sewing work, if the sewing direction is to be changed while the sewing machine needle 1 is stuck in the cloth, that is, in the needle-down state, the foot pedal 28 is returned to the "neutral" state, and the pedal detection circuit is activated. From 30, the FF circuit 62 of the sewing machine control circuit 34 is caused to output the operation command signal Si of "0". Since the FF circuit ⁶² continues to output the start signal SRT of "1" to the speed control circuit 32 until the stop is ready, the rotation speed of the sewing machine drive motor 14 is kept at the ^8th speed. As shown in the figure, it is maintained at a predetermined speed that is j? lower than the normal sewing speed.

During this stop preparation period, the low speed detection circuit ⁷⁶ , as described above, feeds a free charge to the capacitor 84 based on the upper position detection signal ϋΡ and the lower position detection signal DΝ from the position detection circuit 24. Charging takes place only during intervals when the positive output of block flop ⁷⁸ is "1". Then, the speed of the motor 14 decreases and the repetition cycle T becomes long, and the output of the inverter 88 becomes "0" only in the section where the charging voltage of the capacitor S4 falls below the predetermined value Vth. The output signal is sent to the NOR circuit 90. Therefore, at the moment when the positive output of the flip-flop ⁷⁸ becomes "0", the reset signal LDN of the FF circuit ⁶² is obtained from the NOR circuit 90, and the rotation speed of the motor 14 becomes When the speed reaches a predetermined low speed, the direction change condition that the sewing machine needle 1 is in the lower position is ^satisfied . A "1" brake signal BK is obtained, and the electric motor 14 is stopped via the brake circuit 10β of the speed control circuit 32.

When thread trimming is to be performed after sewing, the foot pedal 28 is released 1) and the photo interrupter ⁴² sends the thread trimming signal S2 of " ₁ " to the mixer. Output to the FF circuit of the thin control circuit. In response to this, the FF circuit ⁶⁴ outputs the start signal SRT of "1" and the low speed signal LLKO (the medium speed signal IMCO may be output as necessary) to the speed control circuit 32, The thread control circuit 0 is actuated to control thread trimming, thread threading, etc. Then, the FF circuit is reset by the upper position detection signal UP of "1" from the position detector, and the electric motor 14 stops with the sewing machine needle 1 positioned at the upper position.

FIGS. 9 and 10 show a second preferred embodiment of the present invention, and parts identical or corresponding to those of the embodiment shown in FIGS. be. In the figure, 26 is a speed K detector attached to the sewing machine upper shaft 11 and detects the driving speed of the sewing machine, 32 is each output of the sewing machine control circuit 34 and the speed command signal VG of the pedal detection circuit 30. is supplied to drive the electric motor 14

-BU EAU

CKPIs motor speed control circuit.

That is, the speed command signal VC of the magnetic sensor section ⁶⁰ of the pedal detection circuit 30, the start command signal SRT of the sewing machine control circuit 34, the stop preparation command signal IMC 0 and the low speed command signal LL 0 , a voltage control circuit ⁹⁴ and a linear correction frequency control circuit 109 supplied with the voltage and frequency command signals obtained from the command circuit 92 , and a voltage control circuit ⁹⁴ . A thyristor converter 110 that converts the three-phase AC voltage to a DC voltage and is connected in series to the output side of the converter 110 via a smoothing circuit 111. Be and be! ) A thyristor inverter power circuit 112 to which the output of the correction frequency control circuit 109 is supplied as an ignition control signal, the output of the command circuit 92 and the brake of the sewing machine control circuit 34 and a brake circuit 106 to which a key signal BK is supplied.

The electromagnetic brake 18 is controlled by the output of

A speed detector is installed in the correction frequency control circuit 109.

26 detection signals are supplied and servo controlled. In addition, the output end of the inverter 112 is connected to the voltage control circuit 94 via a transformer 1G1, and the voltage is stabilized by feedback. The output of the abnormal current detection current transformer 113 interposed in the smoothing circuit 111 is supplied, and this detection output cuts off the converter drive current and stops the motor 14. Let

The sewing machine control circuit 34 including the pedal detection circuit 30, the low position detection circuit ⁷⁶ , etc. is constructed in the same manner as in FIGS. 3, 4 and 5 of the above embodiment.

The second preferred embodiment of the present invention is composed of the above configuration. The operation will be explained below.

When starting the sewing work, the foot pedal 28 is depressed to bring the magnet 52 closer to the Hall element 58, and the sewing speed command signal VC is output from the magnetic sensor section SO to the motor speed control circuit 32. At the same time, the photointerrupter 44 outputs an operating signal Si of "1" to the sewing machine control circuit 34. Along with this, a start signal SRT of "1" is output from the sewing machine control circuit 34 to the speed control circuit 32, and the driving of the electric motor 14 is started. Then, in the speed control circuit 32, the voltage and frequency are converted to match the commanded speed by the voltage control circuit 94 and the frequency control circuit ⁹⁶ , and the motor 14 is rotated at a predetermined speed.

When decelerating during sewing work, the value of the sewing speed command signal VC is decreased ^] ) by returning the foot pedal ²⁸ ]). The inverter 110 and the inverter circuit 112 are converted into an inverter and a converter, respectively, and perform regenerative braking using the induction motor core 14 as the power generation core. As a result, the speed is rapidly decelerated and stabilized at the desired middle speed rotation according to the amount of depression.

During such sewing work, the sewing machine needle 1 is placed on the fabric. When changing the sewing direction in the stabbed state, that is, in the needle-down state, the foot pedal 28 is returned to the "neutral" state, and the pedal detection circuit 30 sends the FF circuit ⁶² of the sewing machine control circuit 34 " 0” to output the operation command signal Si. The FF circuit ⁶² keeps outputting the start signal SRT of "1" to the speed control circuit 32 until it is ready to stop. The sewing speed is maintained at a predetermined speed U lower than the normal sewing speed.

During this stop preparation period, the low-speed detection circuit ⁷⁶ causes the capacitor 84 to generate a flip-flop based on the upper position detection signal UP and the lower position detection signal DN from the position detection circuit 24, as described above. Charging occurs only during intervals when the positive output of block 78 is "1". Then, the speed of the electric motor 14 decreases and the repetition period T becomes longer! ) The output of the invark ⁸⁸ sends an output signal of "0" to the NOR circuit ⁹⁰ only in the interval when the charged voltage of the capacitor 84 exceeds the predetermined value Vth. Therefore, at the instant when the positive output of flip-flop ⁷⁸ becomes "0", the NOR circuit

The reset signal LDN of the FF circuit 62 is obtained from 90, the rotational speed of the electric motor 14 reaches a predetermined low speed, and the sewing machine needle 1 is at the lower position. At this point, a brake signal BK of "1" is obtained from the brake one-shot circuit ⁶⁸ , and the electric motor 14 is driven through the brake circuit ¹⁰⁶ of the speed control circuit 32. Stop.

When performing thread trimming 3 after sewing, lift the foot pedal 28.

OMPI ]) Thread trimming that is "1" from the photo interrupter 42! ? The signal _S2 is output to the FF circuit ⁶⁴ of the sewing machine control circuit. In response to this, the FF circuit β4 outputs the start signal SRT of "1" and the low speed signal LLKO (the medium speed signal IMGO may be output as necessary) to the speed control circuit 32, The thread control circuit ⁷⁰ is operated to control thread cutting, thread wiping, etc. Then, the FF circuit ⁶⁴ is reset by the upper position detection signal UP of "1" from the position detector 26, and the sewing machine drive motor 14 stops with the sewing machine needle positioned at the upper position. .

In the above two preferred embodiments, the case where the speed command and the run command are operated by the foot pedal 28 has been explained, but they may be operated by an external run switch signal.

Here, another embodiment will be briefly described. In a sewing machine having a sewing machine vertical shaft, the above-described electric motor rotor 40, position detector 24, and electromagnetic brake are attached to the vertical shaft of the sewing machine. Put on key 18. As the motor, any motor that has a stator and rotor and is suitable for sewing machines, such as a direct current motor, an induction motor, a pulse motor, etc., can be used. is. When using a motor having a braking effect such as a pulse motor, the above brake can be dispensed with. is attached to the outer extension of the sewing machine upper shaft 11 on the outside of the sewing machine frame 10, while the motor stator ³⁸ and the rotor 40 are attached to the sewing machine frame.

CVP1 i:0 10, but the mounting position is not limited and can be selected arbitrarily. For example, it is possible to mount everything within the sewing machine frame 10 or vice versa.

Furthermore, the speed detector 26 can be used as the position detector. It can be used for the control of

As described above, the electric sewing machine according to the present invention can greatly omit the parts necessary for the connection between the electric motor and the sewing machine mechanism, thereby greatly simplifying the configuration of the entire sewing machine. Moreover, compactness and low cost can be achieved.

OMPI

Claims

Amended claims — Λ (accepted by the International Bureau on 18 April 1983 (18.04.83)) [Claims 1 to 7 amended, claims 8, 9 and 10 withdrawn; The content of the IF claims is as follows. ]

1. A sewing machine shaft for reciprocating the sewing machine needle, a sewing machine frame that rotatably supports the sewing machine shaft, an electric motor that drives the sewing machine shaft, and the position of the sewing needle. and a position detecting means for detecting the force and transmitting the detected force to the operation control means of the electric motor, wherein the stator of the electric motor is mounted on the sewing machine frame and , An electric sewing machine characterized in that the rotor of the electric motor and the position detecting means are mounted on the sewing machine shaft.

2- The electric sewing machine according to claim 1, characterized in that the motor is an induction motor.

3. The invention according to claim 1, characterized in that the stator of the electric motor is arranged inside the sewing machine frame, and the position detecting means is arranged outside the sewing machine frame. Electric sewing machine o

4. A sewing machine shaft for reciprocating the sewing machine needle, a frame for rotatably supporting the sewing machine shaft, an electric motor for driving the sewing machine shaft, and detecting the position of the sewing machine needle. position detection means for transmitting the detected output to the operation control means of the electric motor; switch means for giving a desired operation command to the operation control means; and electromagnetic brake means for braking the rotational drive of the sewing machine shaft controlled by the operation control means. An electric sewing machine characterized by being mounted on the sewing machine shaft together with the needle and the position detecting means.

C: VFI L

5. The electric sewing machine o according to claim 4, characterized in that the motor is an induction motor.

6. The machine according to claim 4, characterized in that the stator of the electric motor is arranged inside the sewing machine frame, and the position detecting means is arranged outside the sewing machine frame. Electric sewing machine o

7. An electric sewing machine according to claim 4, characterized in that the switch means includes a pedal switch.