GB2288821A

GB2288821A - Sewing machine drive

Info

Publication number: GB2288821A
Application number: GB9508586A
Authority: GB
Inventors: Shigeru Furugaki; Jiro Ishibashi
Original assignee: Juki Corp
Current assignee: Juki Corp
Priority date: 1994-04-27
Filing date: 1995-04-27
Publication date: 1995-11-01
Also published as: ITTO950327A1; CN1118392A; GB9508586D0; BR9501777A; ITTO950327A0; DE19515571A1; KR950032805A; IT1279141B1; JPH07289767A; TW284803B

Description

ah a 2288821 DRIVING APPARATUS IN A SEWING MACHINE This invention relates

to a driving apparatus in a sewing machine, and more particularly to a so-called "clutch motor,, which is used for automatically stopping the needle bar at a predetermined position.

FIG. 4 shows a so-called "clutch motor Cw which is a driving apparatus in a sewing machine. In the clutch motor CM, a main motor's rotor section R, a clutch plate CP, a motor shaft S, and a motor pulley P are equal in arrangement to those in an ordinary clutch motor.

In the clutch motor CM, a brake board B is rotatable with respect to the motor shaft S and a motor frame. A spiral gear G is cut in the outer periphery of the brake board B. An auxiliary motor SM for low speed rotation is coupled to one end of an auxiliary motor shaft SS, to the other end of which a magnet brake MB is attached. The auxiliary motor shaft SS has a worm W which is engaged with the aforementioned helical gear G.

In the clutch motor CM, similarly as in an ordinary clutch motor a motor lever L is pushed downwardly to press the clutch plate CP against a flywheel F, as a result of which the motor shaft S and the motor pulley P are rotated at 0.

high speed.

When the motor lever L is pushed upwardly, the clutch plate CP is pressed against the brake board B having the helical gear G. In this case, the magnet brake MB is released by a low speed signal or a needle bar predetermined position signal which is externally provided, so that the auxiliary motor SM is rotated. As the auxiliary motor SM is rotated in this manner, the brake board B is turned through the engagement of the worm W with the helical gear G. Thus, the clutch plate CP, the motor shaft S, and the motor pulley P are rotated at low speed.

Next, by suspending the application of the low speed signal or by providing a needle stop signal to suspend the application of the signal to the auxiliary motor, the magnet brake MB is operated to stop the low speed rotation of the motor pulley P.

A device for stopping a needle bar at a predetermined position (hereinafter referred to as "a needle bar predetermined position stop device", when applicable) for a sewing machine which uses an ordinary clutch motor has been disclosed by Unexamined Japanese Utility Model Publication No. Sho. 53-17468. The arrangement of the device is as shown in FIG. 5.

In FIG. 5, reference numeral 1 designates a sewing machine arm; 19, an ordinary clutch motor; 14, an auxiliary motor for low speed rotation which is used to the needle bar A is at a predetermined position; 7, a coupling unit having a oneway rotary clutch; 22, an actuator for moving the motor lever 20 of the clutch motor 19 to the position where the clutch plate is not in contact with the rotor side nor with the brake side; and 26, a switch unit for outputting a top dead point stop instruction signal and a bottom dead point stop instruction signal. FIG. 6 shows the actuator 22 in detail, and FIG. 7 shows the switch unit 22 in detail.

The auxiliary motor 14 is coupled through the coupling unit 7 to the arm shaft 2 of the sewing machine arm 1. The one-way rotation clutch in the coupling unit 7 is so designed that it is freely rotatable in the direction of reverse rotation of the sewing machine. The rotation of the clutch motor 19 is transmitted through a flywheel 4 and an endless belt 37 to the arm shaft 2. A motor lever 20 and a pedal 36 are connected to coupling rods 25 and 29, respectively, which are coupled through the switch unit 26 to each other. The switch unit 26 has a top dead point stop position switch 27 and a bottom dead point stop position switch 28 which are operated as follows: That is, a lever 32 secured to the coupling rod 29 is moved up and down to operate those switches 27 and 28.

When, in the needle bar predetermined position stop device thus organized, the pedal 36 (shown in FIG. 5) is stepped forwardly, the coupling rod 29 is pulled downwardly. In this operation, the coupling rod 29 and the lever 32 are P A is moved downwardly while the compression spring 34 is being compressed, because the compression spring 34 (in FIG. 7) is smaller in elastic force than a return spring provided for the motor lever 20. As a result, a thrust collar 30 secured to the coupling rod 29 is abutted against the bracket of the switch unit 26.

When the pedal 36 is further stepped forwardly, the coupling rod 39, the switch unit 26, and the coupling rod 25 secured to the bracket of the latter 26 are move downwardly as one unit. As a result, a thrust collar 24 secured to the coupling rod 25 pushes the motor lever 20 downwardly against the elastic force of the return spring of the motor lever 20 as viewed in FIG. 6, and finally, in the clutch motor 19, the clutch plate is pressed against the rotor, so that the sewing machine is rotated at high speed. In this operation, the rotation of the clutch motor 19 is transmitted through the endless belt 37 and the flywheel 4 to the arm shaft 2, but the transmission of rotation to the auxiliary motor 14 is inhibited by the one-way rotation clutch in the coupling unit When the pedal 38 is returned to the initial position, the above- described series of operations are effected in the reverse order. Finally, the lever 32 secured to the coupling rod 29 is disengaged from the switch 28 by the returning elastic force of the compression spring 34, so that the switch 28 is turned off. In response to this Ion---ofC signal of the switch 28. a needle bar bottom dead point position stop instruction is applied to a control box 35, as a result of which first the actuator 22 (FIG. 6) is operated.

The body of the actuator 22 is fixedly secured to the motor lever 22, and a plunger 38 provided on the push side of the latter is in contact with the motor frame. Hence, when the actuator 22 is operated, the motor lever 20 is moved downwardly. The amount of downward movement of the motor lever 20 is so determined that, in the clutch motor 19, the clutch plate is not in contact with the rotor side nor with the brake side. Hence, when the actuator 22 is operated, the motor shaft of the clutch motor 19 is made freely rotatable.

Next, the auxiliary motor 14 is rotated, so that the arm shaft 2 is rotated through the one-way rotation clutch in the coupling unit 7. When, during the rotation of the arm shaft 2, a bottom dead point position signal from the flywheel 4 or the coupling unit 7 is received, the auxiliary motor 14 is stopped, and the actuator 22 is turned off. As a result, the motor lever 22 is returned by the elastic force of the return spring, so that, in the clutch motor 19, the clutch plate is pressed against the brake board, whereby the sewing machine is stopped.

When the pedal 36 is stepped backwardly, the coupling rod 29 and the lever 32 secured to the latter 29 are moved upwardly against the compressive elastic force of the I-Ma b j compression spring 33 because the upward movement of the coupling rod 25 and the bracket of the switch unit 26 secured to the former 25 is limited by the coupling rod 25 and the motor frame. As a result, the switch 27 is turned on, and the thrust collar 31 fixedly secured to the coupling rod 29 is abutted against the switch bracket to push the latter upwardly, so that the backward depression of the pedal 36 is stopped.

When the switch 27 is turned on in the abovedescribed manner, a needle bar top dead point position stop instruction is applied to the control box 35. As a result, similarly as in the case of the above-described bottom dead point position stop operation, the actuator 22 and the auxiliary motor 14 are operated, and a top dead point position signal from the flywheel 4 or the coupling unit 7 is received. Hence, similarly as in the case of the bottom dead point position stop operation, the sewing machine stopped.

However, the conventional clutch motor CM shown in FIG. 4 suffers from the following problems:

(1) When it is braked abruptly, an inertial force produced by the rotation of the clutch plate CP is applied to the engaging region of the helical gear G and the worm W, thus being liable to produce an impact force.

(2) The braking operation is effected through the engagement of the helical gear G and the worm W. Hence, the motor pulley P has a play in the direction of rotation as -6 h A much as the backlash of the helical gear G and the worm W.

(3) When the magnet brake MB becomes output of order; that is, when the motor cannot be braked, the motor pulley cannot be stopped. If the magnet brake MB is removed from the motor for replacement or repair, then it is impossible to use the motor as an ordinary clutch motor.

The conventional needle bar predetermined position stop device shown in FIGS. 5 through 7 suffers from the following difficulties:

(1) In the top dead point stop operation or in the bottom dead point stop operation, the auxiliary motor 14 must be operated after the motor lever 20 is stepped to the predetermined position so that the clutch plate is not in contact with the rotor side nor the brake side. That is, the operations are performed stepwise. Hence, the series of operations for stopping the needle bar at the predetermined position take time, being long in cycle time.

(2) The clutch motor has two positions, one on the rotation side and the other on the stop side, for the clutch plate, similarly as in a conventional clutch motor, and, in addition, the neutral position where the clutch plate is not on the rotation side nor on the stop side. Hence, the clutch motor must have a relatively large space for the clutch plate. And it is not permitted to extremely decrease the stroke of forward depression of the pedal. If the stroke is forcibly decreased, then the movement of the motor lever 2 must be extremely increased in accuracy.

(3) When the clutch plate or the brake board is worn, or when they are replaced being worn, the motor lever 20 is changed in position. Accordingly, it is necessary to adjust the position of the actuator 22 with respect to the motor lever 20.

(4) If the return spring of the motor lever 20 is extremely great in elastic force, then the operation of the actuator becomes unsatisfactory. Accordingly, in this case, it is impossible for the clutch plate to completely disengage from the brake board, so that the auxiliary motor 14 is rotated while being overloaded by the brake board. As a result, the auxiliary motor 14 or the one-way rotation clutch in the coupling unit 7 may be broken.

In view of the foregoing, an object of the invention is to provide a driving apparatus for a sewing machine which is free from the difficulties that, when it is abruptly braked, the impact force produced by the inertial force of rotation of the clutch plate is transmitted to a rotation transmitting section adapted to transmit the rotation of the auxiliary motor, and, when the auxiliary motor is not in rotation, the play of the rotation transmitting section is transmitted to the motor pulley to cause the latter to play in the direction of rotation.

A To achieve the object, a first aspect of the present invention provides a driving apparatus in a sewing machine comprising: a main motor having a rotor; a flywheel integral with the rotor of the main motor; a motor shaft; a clutch plate integral with the motor shaft, the clutch plate confronted with the flywheel; a motor pulley mounted on the outer end portion of the motor shaft; a rotary member rotatably mounted on the motor shaft between the motor pulley and the clutch plate; an auxiliary motor; a rotation transmitting device for transmitting a rotation of the auxiliary motor to the rotary member; a motor lever for moving the motor shaft, the motor lever being operated to selectively press the clutch plate against one of the flywheel and the rotary member to transmit a rotation to the motor pulley; and an auxiliary brake device directly braking the rotary member to stop the rotary member, selectively.

A second aspect of the invention provides a driving apparatus according to the first aspect, wherein the auxiliary brake device has a spring for maintaining the rotary member braked.

A third aspect of the invention provides a driving apparatus according to the first aspect, wherein the rotation transmitting device has a gear mechanism provided between the auxiliary motor and the rotary member.

A fourth aspect of the invention provides a driving apparatus according to the first aspect, wherein the rotation transmitting device comprises: an auxiliary gear connected with the auxiliary motor; and a timing belt laid over the auxiliary gear and the rotary member.

In the sewing machine driving apparatus according to is the invention, the rotary member which is rotatable around the motor shaft and to which the rotation of the auxiliary motor is transmitted is stopped being directly braked by the auxiliary brake device. Hence, when the clutch motor is abruptly braked, the impact force produced by the inertial force of rotation of the clutch plate is not transmitted to the rotation transmitting device provided between the auxiliary motor and the rotary member. In addition, when the auxiliary motor is not in operation, the play of the rotation transmitting device is not transmitted which otherwise may cause the motor pulley to play in the direction of rotation.

In the invention, a method of setting the motor lever at the neutral position to make the motor shaf t rotatable is not employed. Hence, the motor shaft having the clutch plate which is pushed against the rotary member or the flywheel integral with the rotor of the main motor, can be stably made rotatable independently of the amount of movement of the motor lever and the motor lever returning elastic force.

In the driving apparatus, the auxiliary brake device has the spring adapted to maintain the rotary member braked Hence, even when the actuator becomes out of order, the braking function is maintained by the elastic force of the auxiliary brake spring.

Furthermore, in the driving apparatus, the rotation transmitting device for transmitting the rotation of the auxiliary motor to the rotary member is the gear mechanism. Hence, when the clutch motor is abruptly braked, the impact force produced by the inertial force of rotation of the clutch plate is not transmitted to the engaging region of the gears in the gear mechanism. In addition, when the auxiliary motor is not in operation, the play in the engaging region of the gears is not transmitted which otherwise may cause the motor pulley to play in the direction of rotation.

Moreover, in the driving apparatus. the rotation transmitting device for transmitting the rotation of the auxiliary motor to the rotary member is the timing belt device. Hence, when the clutch motor is abruptly brake, the impact force produced by the inertial force of rotation of the clutch plate is not transmitted to the engaging region of the timing the timing pulley and the timing belt. In addition, when the auxiliary motor is not in operation, the slackening of the timing belt is not transmitted to the motor pulley, which prevents the motor pulley from playing in the direction of rotation.

In the accompanying drawings:

FIG. 1 is a longitudinal sectional view of an example of a clutch motor provided as a driving apparatus in a sewing -11 2 machine, which constitutes a first embodiment of the invention; FIG. 2 is a longitudinal sectional view of another example of the clutch motor, which constitutes a second embodiment of the invention; FIG. 3 is also a longitudinal sectional view of another example of the clutch motor, which constitutes a third embodiment of the invention; FIG. 4 is a longitudinal sectional view of an example of a clutch motor of a conventional driving apparatus in a sewing machine; FIG. 5 is a front view outlining an example of a conventional needle bar predetermined position stop device in a sewing machine; FIG. 6 is an enlarged diagram showing an actuator in the stop device of FIG. 5 in detail; and FIG. 7 is an enlarged diagram showing a switch unit in the stop device of FIG. 5 in detail.

Preferred embodiments of the invention will be described with reference to FIGS. 1 through 3.

FIG. 1 shows a clutch motor as a driving apparatus in a sewing machine, which constitutes a first embodiment of the invention. In FIG. 1, reference numeral 50 designates the clutch motor, 51, a motor frame; 52, the rotor of a main motor; 55, a flywheel; 56, a slide sleeve; 58, a motor shaft; 59, a motor pulley; 61, a clutch plate; 62, a motor lever; 64, a motor lever returning spring; 65, a rotary member; 66, a helical gear; 67, a brake board; 71, a worm; 72, an auxiliary motor shaft; 74, a rotation transmitting device; 75, an auxiliary motor; 81, an auxiliary brake device; 82, an auxiliary brake pad; 84, an auxiliary brake spring; and 87, an actuator.

As shown in FIG. 1, in the clutch motor 50, the motor frame 51 accommodates the main motor's rotor 52, the shaft 53 of which is rotatably supported through bearings 54 and 54. The right end of the rotor shaft 53, as viewed in FIG. 1, merges with the flywheel 55. The slide sleeve 56 is slidably fitted in the right end portion of the motor frame 51 as viewed in FIG. 1. In the slide sleeve 56 thus fitted, the motor shaft 58 is rotatably supported through bearings 57 and 57 in such a manner that the motor shaft 58 is coaxial with the aforementioned rotor shaft 53.

The motor pulley 59 is fixedly mounted on the outer end portion of the motor shaft 58 protruding from the motor frame 51 in such a manner that it appears outside. The clutch plate 61 is integral with the inner end portion of the motor shaft 58 extending inside the motor frame 51, in such a manner that the clutch plate 61 is confronted with the flywheel 55. An endless belt (not shown) is laid over the motor pulley 59 and the pulley mounted on the arm shaft of 1 is the sewing machine arm as is well known in the art.

The above-described slide sleeve 56 is connected to the motor lever 62. The latter 62 is pivotally mounted on a pin 63 embedded in the motor frame 62. In order to urge the slide sleeve 56 to the right as viewed in FIG. 1, one end of the motor lever returning spring 64, which is a tension coil spring, is connected to the motor lever 62 between the pin 63 and the slide sleeve 56, while the other end is connected to the right part of the motor frame 51.

The rotary member 65 is rotatably mounted on the motor shaft 58 between the slide sleeve 56 and the clutch plate 61. The rotary member 65 includes the helical gear 66 on the left side and the brake board 67 on the left side; that is, the rotary member 65, the helical gear 66 and the brake board form one unit. The right end portion of the rotary member 65 is rotatably supported through a bearing 68 on the motor frame 51.

The worm gear 71, being arranged across the helical gear 66, is engaged with the latter 66. The worm gear 71 is fixedly mounted on the auxiliary motor shaft 72. The auxiliary motor 75 having the auxiliary motor shaft 72 is fixedly secured through a motor cover 76 to the outer surface of the motor frame 51. In order to transmit the rotation of the auxiliary motor 75 to the rotary member 65, the rotation transmitting device 74 is provided which comprises the worm 71 of the auxiliary motor 71f and the helical gear 66.

is In order to brake the brake board 67, the auxiliary brake device 81 is provided. The auxiliary brake device 81 comprises: the aforementioned auxiliary brake pad 82 adapted to press the outer cylindrical surface of the brake board 67; a rod 83 to which the auxiliary brake pad 82 is connected; the aforementioned auxiliary brake spring 84 provided between the auxiliary brake pad 82 and the motor frame 51. More specifically, the auxiliary brake spring 84 is a compression coil spring which is wound on the rod 83 to push the auxiliary brake pad 82 against the outer cylindrical surface of the brake board 67.

The left end portion (in FIG. 1) of a link 85 is coupled to the outer end portion of the rod 83 protruding outside from the motor frame 51. The middle portion of the link 85 is supported by a pin 86 embedded in the motor frame in such a manner that the link 85 is swingable about the pin 86. The right end portion (in FIG. 1) of the link 85 is coupled to the operating rod 88 of the actuator 87 which is fixedly mounted on the outer surface of the motor frame 51. The actuator 87 may be a solenoid, an air cylinder or a hydraulic cylinder, or may be any other driving source.

The clutch motor 50 thus designed operates as follows:

It is assumed that the main motor's rotor 52 is being rotated at high speed, and the auxiliary motor 75 is at rest. In this case, the actuator 87 of the auxiliary brake device 81 is not in operation, and accordingly the auxiliary brake pad 82 is kept pressed against the outer cylindrical surface of the brake board 67 by the compressive force of the auxiliary brake spring 84. That is, the rotary member 65 having the helical gear 66 is held stopped being braked directly by the auxiliary brake device 81.

Under this condition, the motor lever 62 is swung about the pin 63 to move the slide sleeve 56 to the left (in FIG. 1) against the elastic force of the motor lever spring 64. In this operation, the motor shaft 58 is moved together with the slide sleeve 56, so that the clutch plate 61 integral with the motor shaft 58 is pushed against the flywheel 55 which is integral with the main motor's rotor 52.

Hence, the main motor's rotor 51 is directly coupled to the motor shaft 58, so that the motor pulley 59 integral with the motor shaft 58 is rotated at high speed.

In the case where it is required to rotate the sewing machine at low speed for instance to stop the needle bar (not shown) at the top or bottom dead point, the motor lever 62 is swung in the opposite direction, so that the clutch plate 61 is pressed against the side surface of the helical gear 66 of the rotary member 65 with the aid of the elastic force of the motor lever returning spring 64. Under this condition, in response to a low speed signal or needle bar predetermined position signal which is provided externally, the auxiliary brake device 81 is released, and the auxiliary motor 75 is 1 rotated.

That is, the actuator 87 is operated to retract the operating rod 88. As a result, the link 85 is swung about the pin 86 to move the rod 83 upwardly, so that the auxiliary brake pad 82 is disengaged from the outer cylindrical surface of the brake board 67 against the compressive elastic force of the auxiliary brake spring 84, to allow the rotary member 65 to freely rotate. Next, the auxiliary motor 75 is started, and the rotation of the latter 75 is transmitted to the rotary member 65 through the engagement of the helical gear 66 and the worm 71 mounted on the auxiliary motor shaft 72. Thus, the rotary member 65 is rotated at low speed.

In this case, the clutch plate 61 is pressed against the side surface of the helical gear 66 of the rotary member 65 as was described above. Hence, the rotary member 65 and the clutch plate 61 are coupled together as if they were directly coupled to each other. Accordingly, the motor pulley 59 fixedly mounted on the motor shaft 59 is rotated at low speed.

Thereafter, in response to the termination of the low speed signal or to a needle stop signal, the auxiliary motor 75 is stopped, while the auxiliary brake device 81 is operated to directly brake the rotary member 65 to stop the latter 65. Thus, the low speed rotation of the motor pulley 59 is stopped.

A second embodiment of the invention will be a described with reference to FIG. 2. The second embodiment is different from the above-described first embodiment in.the arrangement of its auxiliary motor 95 and its rotation transmitting device 94. Hence, in FIG. 2, parts corresponding functionally to those which have been described with reference to the first embodiment shown in FIG. 1 are therefore designated by the same reference numerals or characters. And the second embodiment will be described with reference mainly to the difference.

In the second embodiment, as shown in FIG. 2, the rotary member 65 has as its part a toothed pulley, namely, a timing pulley 69 (instead of the helical gear 66) on the left side. A timing belt 91, which is a toothed belt, is laid over the timing pulley 69. The timing belt 91 is laid over a gear 92, too.

The gear 92 is fixedly mounted on the output shaft 93 of the auxiliary motor 95. The latter 95 is fixedly mounted through a motor cover 96 on the outer surface of the motor frame 51. In order to transmit the rotation of the auxiliary motor 95 to the rotary member 65, the gear 91 of the auxiliary motor 95, the timing belt 91, and the timing pulley form a rotation transmitting device 94.

With the rotation transmitting device 94, the rotation of the auxiliary motor can be transmitted to the rotary member 65. More specifically, when the auxiliary motor is driven, the low speed rotation can be transmitted is from the gear 92 mounted on the auxiliary motor shaft 93 through the timing belt 91 and the timing pulley 91 to the rotary member 65. The other operations of the second embodiment are the same as those of the first embodiment.

The above-described first and second embodiments of the invention have the following effects:

(1) With respect to the problems (1) and (2) accompanying the conventional clutch motor shown in FIG. 4: The helical gear 66 or the timing pulley 69 is directly braked by the auxiliary brake device 81. Hence, when the clutch motor is abruptly braked, the impact force produced by the inertial force of rotation of the clutch plate is not applied to the engaging region of the helical gear 66 and the worm or the timing pulley 69 and the timing belt 91. And when the auxiliary motor is not in operation, the backlash of the helical gear 66 and the worm 71, or the slackening of the timing belt 91 will not cause the motor pulley 59 to play in the direction of rotation.

(2) With respect to the problems (1) through (4) accompanying the conventional needle bar predetermined position stop device shown in FIGS. 4 through 7: In the invention, a method of setting the motor lever 62 at the neutral position to make the motor shaft 58 freely rotatable is not employed. Hence, the motor shaft 58 can be stably made rotatable independently of the amount of movement of the motor lever 62 and accordingly the amount of movement of the clutch plate 61 and independently of the returning elastic force of the motor lever 62.

(3) With respect to the problem (3) accompanying the conventional clutch motor shown in FIG. 4: Even when the actuator 87 becomes out of order, the braking function is maintained by the elastic force of the auxiliary brake spring 84. Hence, even in the case where the actuator 87 is removed for replacement or repair, the clutch motor 50 remains unchanged in function.

A third embodiment of the invention will be described with reference to FIG.. 3. The third embodiment is different from the first embodiment only in the arrangement of its auxiliary brake device 81. Hence, in FIG. 3, parts corresponding functionally to those which have been described with reference to the first embodiment shown in FIG. 1 are therefore designated by the same reference numerals or characters. And the third embodiment will be described with reference mainly to the difference.

In the third embodiment, the auxiliary brake device 81 adapted to brake the brake board 6 is designed as follows: As shown in FIG. 3, the brake pad 82 adapted to press the outer cylindrical surface of the brake board 66 is fixedly mounted on one end of the rod 83, and the left end portion (in FIG. 3) of the bell crank 185 is coupled to the outer end portion of the rod 83 protruding outside from the motor frame 51. An auxiliary brake spring 184, which is a compression is coil spring, is wound on the outer end portion of the rod 83 protruding outside from the motor frame 51. More specifically, the auxiliary brake spring 184 is interposed between the outer surface of the motor frame 51 and the left end portion (in FIG. 2)of the bell crank 185, to urge the auxiliary brake pad 82 to space from the outer cylindrical surface of the brake board 67.

The middle portion of the bell crank 185 is mounted on a pin 186 embedded in the motor frame 51 in such a manner that the bell crank 185 is swingable about the pin 186. The upper end portion of the bell crank 185 as viewed in FIG. 3 is coupled to the operating rod 188 of an actuator 187. The actuator 187 is fixedly mounted through a bracket 189 on the outer surface of the motor frame 51. Similarly as in the case of the first embodiment, the actuator 187 may be a solenoid, an air cylinder or a hydraulic cylinder, or may be any other driving source.

In the auxiliary brake device 81 of the third embodiment, the movement of the operating rod 188 of the actuator 187 is opposite to that of the operating rod 88 of the actuator 87 in the first embodiment. That is, when the actuator 187 of the auxiliary brake device 81 is operated, the operating rod 188 is retracted to the left. As a result, the bell crank 185 is swung about the pin 186 to move the rod 83 downwardly against the elastic force of the auxiliary brake spring 184, so that the auxiliary brake pad 82 is is pressed against the outer cylindrical surface of the brake board 67. Thus, the rotary member 65 is stopped being directly braked.

When the auxiliary brake device 81 is released, the actuator 187 is deenergized, so that the operating rod 188 is moved to the right. As a result, the bell crank 185 is swung about the pin 186 to move the rod 83 upwardly, so that the auxiliary brake pad 82 is left from the outer cylindrical surface of the brake board 67 being assisted by the elastic force of the auxiliary brake spring 184. rotary member 65 is set freely rotatable.

As a result, the The other operations are the same as those of the first embodiment.

The arrangement of the auxiliary brake 81 in the third embodiment may be applied to the second embodiment.

The clutch motor 50 having the above-described auxiliary brake device 81 of the third embodiment has effects which are equivalent to the abovedescribed effects (1) and (2) of the first and second embodiments.

While the invention has been described with reference to the clutch motor which is a driving apparatus in a sewing machine, it should be noted that the invention is not limited thereto or thereby. That is, the technical concept of the invention may be applied to other driving apparatus such as other clutches and motors. In addition, the technical concept of the invention may be applied to all kinds of sewing machines. It goes without saying that other concrete structures such as for instance the rotation transmitting device provided between the auxiliary motor and the rotary member may be changed or modified without departing from the invention.

As was described above, in the sewing machine driving apparatus of the invention, the auxiliary brake device directly brakes the rotary member which is rotatable around the motor shaft and to which the rotation of the auxiliary motor is transmitted, to stop it. Hence, when the clutch motor is abruptly braked, the impact force produced by the inertial force of rotation of the clutch plate is not transmitted to the rotation transmitting device provided between the auxiliary motor and the rotary member. In addition, this feature eliminates the difficulty that, when the auxiliary motor is not in operation, the play of the rotation transmitting device is not transmitted which otherwise may cause the motor pulley to play in the direction of rotation.

In the invention, a method of setting the motor lever at the neutral position to make the motor shaft rotatable is not employed. Hence, the motor shaft having the clutch plate which is pushed against the rotary member or the flywheel integral with the rotor of the main motor, can be stably made rotatable independently of the amount of movement of the motor lever and the motor lever returning elastic force.

Furthermore, in the driving apparatus of the is invention, the auxiliary brake device has the spring adapted to maintain the rotary member braked. Hence, even when the actuator becomes out of order, the braking function is maintained by the elastic force of the auxiliary brake spring. Hence, even in the case where the actuator is removed for replacement or repair, the clutch motor remains unchanged in function.

Still further, the rotation transmitting device for transmitting the rotation of the auxiliary motor to the rotary member is the gear mechanism. Hence, when the clutch motor is abruptly braked, the impact force produced by the inertial force of rotation of the clutch plate is not transmitted to the engaging region of the gears in the gear mechanism. When the auxiliary motor is not in operation, the backlash of the engaging region of the gears is not transmitted to the motor pulley, which prevents the motor pulley from playing in the direction of rotation.

Still further, the rotation transmitting device for transmitting the rotation of the auxiliary motor to the rotary member is the timing belt device. Hence, when the clutch motor is abruptly braked, the impact force produced by the inertial force of rotation of the clutch plate is not transmitted to the engaging region of the timing pulley and the timing belt. When the auxiliary motor is not in operation, the play in engagement of the timing pulley and the timing belt, or the slackening of the timing belt is not transmitted to the motor pulley, which otherwise may cause the motor pulley to play the direction of rotation.

Claims

CLAIMS 1 2 3 4 5 6 7 8 9 10 11 12 13 14 is 16 17 18 19 20 21 22 23 1. A driving apparatus in a sewing machine comprising: main motor having a rotor; flywheel integrated with said rotor of said main motor; motor shaft provided separately from said rotor of said main motor; a clutch plate integrated with said motor shaft, said clutch plate facing said flywheel; motor pulley mounted on said motor shaft at one end thereof; rotary member rotatably mounted on said motor shaft and disposed between said motor pulley and said clutch plate; an auxiliary motor; means for transmitting a rotation of said auxiliary motor to said rotary member; a motor lever for moving said motor shaft, said motor lever being operated to selectively abut said clutch plate against one of said flywheel and said rotary member to transmit either rotation of said flywheel or said rotary member to said motor pulley; and an auxiliary brake device directly braking said rotary member to stop said rotary member, selectively. k 1 2 3 4 5 6 2. A driving apparatus according to claim 1, wherein said transmitting means comprises: an auxiliary gear connected with said auxiliary motor; and a timing belt extending over said auxiliary gear and said rotary member. 1 2 3 3. A driving apparatus according to claim 1, wherein said transmitting means has a gear mechanism provided between said auxiliary motor and said rotary member.

1

2

3

4 5 1 2 3 4. A driving apparatus according to claim 3, wherein said gear mechanism comprises:

helical gear provided on said rotary member; and worn mounded on said auxiliary motor, said worn meshing with said helical gear.

5. A driving apparatus according to claim 1, wherein said auxiliary brake device has a spring for maintaining said rotary member in a brake condition.

1 2 3 4 1 3 2 4

6. A driving apparatus according to claim 5, wherein said transmitting means comprises:

an auxiliary gear connected with said auxiliary motor; and a timing belt extending over said auxiliary gear and said rotary member.

7. A driving apparatus according to claim 5, wherein said transmitting means has a gear mechanism provided between said auxiliary motor and said rotary member.

8. A driving apparatus according to claim 7, wherein said gear mechanism comprises:

i 0 1 2 3 4 6 7 8

9 1 2 3 4 5 6 7 8 9 10 1 2 9. A driving apparatus according to claim 5, wherein said auxiliary brake device further comprises: an auxiliary brake pad for pressing the outer cylindrical surface of said rotary member; an operating member connected with said auxiliary brake pad, said operating member movable for said auxiliary brake pad to selectively press against said outer cylindrical surface of said rotary member and release from said outer cylindrical surface of said rotary member; and an actuator for moving said operating member.

10. A driving apparatus according to claim 1, wherein said auxiliary brake device comprises: an auxiliary brake pad for pressing the outer cylindrical surface of said rotary member; an operating member connected with said auxiliary brake pad, said operating member movable for said auxiliary brake pad to selectively press against said outer cylindrical surface of said rotary member and release from said outer cylindrical surface of said rotary member; and an actuator for moving said operating member.

11. A driving apparatus according to claim 10, wherein said actuator comprises one of a solenoid, an air cylinder and an oil cylinder.

1 2 3 4 1 2 3 4 5 12. A driving apparatus according to claim 10. wherein said auxiliary brake pad is slidable in a perpendicular direction to the axial direction of said motor shaft.

13. A driving apparatus according to claim 1, wherein said motor shaft is slidable between a first position that said clutch plate is contact with said flywheel and a second position that said clutch plate is contact with said rotary member.

i