US3598071A - Electrically driven sewing machine with means for stopping the machine in a predetermined position of the needle bar - Google Patents

Abstract

Arrangement for stopping the needle bar in a predetermined position on sewing machines with electrical motor drive means, where upon turning off the machine in a random position of the needle bar with a hand lever by way of a transfer lever of limited range of movement and a switch lever, a disconnecting element connected therewith is swung into the path of rotation of a retarding member that rotates with the arm shaft and a switch in the motor circuit are actuated so that by way of the switch 62 which is secured thereto the switch lever 60 rests in a force transmitting manner against the transfer lever 55 and the retarding member 11, 14 has an annular abutment surface 15, 16 that is interrupted by a disconnecting groove 69 for the disconnecting element 68.

Description

United States Patent Inventors Lucian Luczak Karlsruhe; Giinter Meier, Weingarten, both of, Germany Appl. No. 18.623 Filed Mar. 11,1970 Patented Aug. 10, 19'" Assignee Firm: G. M. Piaf! Ag Kaiserslautern. Pfalz. Germany Priority Mar. 29, 1969 Germany G 69 12 817 ELECTRICALLY DRIVEN SEWING MACHINE WITH MEANS FOR STOPPING THE MACHINE IN A PREDETERMINED POSITION OF THE NEEDLE BAR 5 Claims, 7 Drawing Figs.

U.S.Cl 112/219A Int. CL D05b 69/22 Fieldofsardl 112/219,

Primary ExaminerH. Hampton Hunter Attorney-Robert H. Jacob ABSTRACT: Arrangement for stopping the needle bar in a predetennined position on sewing machines with electrical motor drive means, where upon turning off the machine in a random position of the needle bar with a hand lever by way of a transfer lever of limited range of movement and a switch lever, a disconnecting element connected therewith is swung into the path of rotation of a retarding member that rotates with the arm shaft and a switch in the motor circuit are actuated so that by way of the switch 62 which is secured thereto the switch lever 60 rests in a force transmitting manner against the transfer lever 55 and the retarding member 11, 14 has an annular abutment surface 15, 16 that is interrupted by a disconnecting groove 69 for the disconnecting element 68.

PATENTEU AUG 1 01971 3598071 SHEET 1 [IF 3 PATENTED AUG 1 0 I971 SHEET 2 BF 3 BACKGROUND OF THE INVENTION The invention relates to electric motor driven sewing machines and is particularly concerned with a machine of the type equipped with means for stopping the machine in a predetermined position of the needle bar. More in particular the invention concerns arrangements of the type where upon interruption of the current supply to the machine in any position in which the needle bar happens to be at the moment, a stopping member is swung into the path of movement of an impeding element that rotates with the arm shaft and a switch I is actuated in the circuit which feeds the motor. This is effected by means of a hand lever actuating a transfer lever of limited movement range and a switch lever connected with the stopping member.

In sewing machines provided with such an arrangement the motor is firmly coupled with the machine. Therefore, during the stopping operation it is supplied with potential and endeavors to drive the machine as long as the hand lever is operated for carrying out the stopping operation. If the hand lever is held too long in that position the danger exists that after the needle has assumed its raised position the forcibly stopped motor burns out.

The known arrangements of this type involve the further shortcoming that the output of the motor must be choked in such a manner to obtain the placement of the needle in raised position, that the stopping shock does not become too strong' as the stopping member contacts the end member, while on the other hand, when the line potential is low, the output must not be so small that the torsion produced by the motor is no longer sufficient to move the machine into the needle raised position.

SUMMARY OF THE INVENTION It is an object of the present invention to overcome these shortcomings and to provide an arrangement whereby the drive motor is automatically disconnected as soon as the desired elevated needle position is reached and which,

moreover, insures of stopping in the exact stopping position.

In accordance with the invention this is accomplished in that the switching lever is in force transmitting engagement with the transfer lever by way of the switch connected with it,

:and that the inhibiting or drag member has an annular abutment surface which is interrupted by a disconnecting groove for the stopping member.

The invention may also be utilized in machines where the actuating lever for the presser foot bar serves as a manual lever. This lever actuates an abutment connected with the transfer lever by means of a catch when it is swung beyond the position required for lifting the presser foot. In accordance with the invention a second abutment projects into the other end region of the path of movement of the catch. The manual lever mentioned thus can be used not only for raising the presser foot while simultaneously initiating the stopping operation after termination of the sewing operation, but it is also possible with the same manual lever to initiate a stopping operation while the presser foot is resting on the material being sewn.

Furthermore it is also possible with such an arrangement by alternately actuating an releasing the manual lever in its end position to initiate a stitch-by-stitch sewing operation while the material presser foot is lowered.

In order to keep the energy that is still present due to the moment of inertia of the drive motor during stopping of the machine in the desired position, away from the driving components of the sewing machine, the arrangement is equipped with an overrunning clutch. The drive motor drives the arm shaft by way of this clutch which may be coupled by means of in that the uncoupling ring has studs associated withthe clamping elements of the overrunning clutch 'w'hich project into corresponding recesses of the clamping elements.

BRIEF DESCRIPTION OF THE DRAWINGS Further advantageous features and details of the invention will become apparent from an embodiment illustrated in the drawing and in which:

FIG. 1 is a schematic front view of partly in section, I

FIG. 2 is an exploded view of the coupling arrangement,

FIG. 3 is a side view of the couplingarrangement,

FIG. 4 is a view drawn to an enlarged scale of the hand lever and the components operatively connected thereto,

FIG. 5 is a schematic illustration of the circuit for driving the sewing machine motor,

FIG. 6 is a section taken along the line VIVI in FIG. 2, and

FIG. 7 is a section taken along the line VII-VII in FIG. 4.

the sewing machine DESCRIPTION OF THE INVENTION The sewing machine comprises in a normal manner the head 2, arm I and the material support plate 3. The arm shaft 4 is joumaled in the arm 1 which is connected by way of its end that extends into the head 2 with transmitting elements, not shown, for driving the needle bar 5 withthe needle 6.

At the other end of the arm shaft 4 the toothed belt disk 7 (FIGS. 2 and 3) of an overrunning clutch is secured by way of a sleeve 8 extending laterally from the disk 7. The toothed belt disk 7 drives the stitch forming tools (not shown) arranged below the material support plate 3 by means of a toothed chain 9.

An uncoupling ring I0 made of plastic material is mounted on the sleeve 8 ofthe toothed belt disk 7 on which the segment member I] is formed which is arranged between the ends I2 and I3 of an annular rib 14 of the toothed belt disk 7 that projects in axial direction. The rib I4 has an abutment surface 15 at the same radial distancefrom the axis of rotation as the abutment surface 16 on the segment member. The end I3 of the rib 14 which is the rearward end taken in the direction of rotation (arrow) has a flattened portion I7 at the end of the abutment surface IS.

A transversely projecting stud I8 of the segment member II projects into a recess I9 of a clamping element 20 in the form of a hollow roller that is disposed in a wedge shaped recess 21 of a coupling disk 22 and is pressed by a leaf spring 23 into frictional engagement with the bearing surface 24 of the coupling disk 22 that encompasses the belt disk 25.

A covering 26 serves for securing the coupling disk 22 to the toothed belt disk 7 by means of screws 27 that are threadedly received through the bores 28 of the coupling disk 22 in threaded apertures 29 of the toothed belt disk 7. They connect the cover ring 26, the coupling disk 22 and the toothed belt disk 7 securely with one another. Simultaneously,v

the cover ring 26 effects securement of the belt disk 25 and of the clamping element 20 against axial displacement.

The segment member II has a limiting abutment 30 which under the influence ofa torsion spring 3| (FIG. 3 ).that at one end engages the segment member II and at. the other end the front endI2 of the rib I4 as seen in the direction of rotation can engage the adjacent screw 27 and thereby limits the movement of the segment member II in the direction toward the end I3 of the rib 14. In this manner the stud 18 does not touch the clamping element 20 in that end position of the un- At the reverse side of the head 2 a manual lever 37 (see also FIG. 4) mounted upon a supporting shaft 38 which is connected with the raising mechanism for the material presser bar 36 of the machine that supports the material presser foot 35 while the end of the shaft 38 that extends into the interior of the head 2 supports a lever arm 39 having a catch 40. Two abutments 42 and 43 of a switch bar guide member 44 which are connected by means of a cam 41 cooperate with the catch 40.

The switch bar guide member 44 is slidably guided upon a stationary stud 47 on the housing by means of a bearing slot 45 upon the supporting shaft 38 and by way of a bifurcated end 46. The limit of the displacement in one direction is determined by the one end 48 and in the other direction by the other end 480 of the bearing slot 45, which cooperates with the supporting shaft. The switching bar 49 connects the switch bar guide member 44 with an angular lever 50 (FIGS. 2 and 3). The angular lever 50 is journaled on a stud 51 on a carrier 52 secured in the arm 1 that rests against the wall of the arm I and extends with its free arm 53 below an arm 54 of a transfer lever 55 that is joumaled upon a belt 56 secured to the carrier 52 and has an arm 57 as well as a switch am 58. One end of a draw spring 59 is hooked onto the arm 57, while the other end of the spring is secured to arm 1.

Furthermore a shifting lever 60 is journaled on the bolt 56 which has an arm 61 having an end switch 62 and a second arm 63 for receiving the end of a spring 64, the other end of which is hooked onto the arm 57 of the transfer lever 55. The spring 64 effects a relative movement of the transfer lever 55 and of the shifting lever 60 so that the switch arm 58 presses against the switch pin 65 of the end switch 62. An abutment lug 67 of the switch arm 58 that engages the housing 66 of the end switch 62 limits the relative movement between the transfer lever 55 and the switch lever 60.

The switch lever 60 is provided with a shutoff member 68 that is adapted to engage the abutment surface of the rib 14 of the toothed belt disk 7 as well as the abutment surface 16 of the segment member 11 and which is so proportioned that it can drop into the space between the segment member 11 of the uncoupling ring 10 and the rib 14 which serves as the shutoff groove 69. The segment member 11 and the rib 14 in this connection form a retarding member for the shutoff member 68. The space 70 between the end 12 of the rib l4 and the segment member II is in its normal position smaller than the dimension of the shutoff member 68 so that this cannot drop into the space 70.

FIG. S shows the circuit diagram of the arrangement.

A line 71 leads from the power connection to the drive motor 34 and a second line 72 leads to the resistor 73 of a conventional starter. The latter is equipped with a sliding contact 74 which is connected by way of a line 75 with a contact 76 of the end switch 62. A rest contact 77 of the end switch 62 com nected with the drive motor 34 by way of a line 78 leads to a line 79 for a contact 80 at the resistor 73 in order to supply a partial potential to the motor 34.

The arrangement operates as follows:

With the material presser foot 35 lowered, the draw spring 59 pulls the end 480 of the bearing slot 45 by way of the transfer lever 55, the angular lever 50 and the switch bar 49 against the supporting shaft 38. As the hand lever 37 is shifted into the position in accordance with FIG. 1, the material presser foot 35 is raised from the material being sewn. At the same time the catch 40 moves the switch bar guide member 44 by way of cam 41 slightly to the left.

In both positions the spring 64 retains the housing 66 of the end switch 62 secured to the switch lever 60 into engagement with theabutment lug 67 of the transfer lever 55. As a result the shutoff member 68 is held in position away from the rib 14 of the toothed belt disk 7.

In this mutual position of the transfer lever 55 and switch lever 60 as the starter is operated by the seamstress the live contact 76 of the end or limit switch 62 is closed by the switch pin 65 which is pressed down and the drive motor 34 drives the belt disk by way of the toothed belt 32 in accordance with the displacement of the sliding contact 74 on the resistor 73. 9 i

Due to the pressure of the clamping element 20 against the bearing track 24 of the belt disk 25, thisdisk' takes along the coupling disk 22 and thus also the toothed belt disk 7 which is firmly connected with the latter.

The toothed belt disk 7 on the one hand drives the arm shaft 4 and thus the needle bar 5 and on the other hand the lower stitch forming tools by way of the toothed chain 9.

Upon terminating the sewing operation the starter (not illustrated) moves to its position of rest. In this connection the sliding contact 74 moves back into its disconnected position and the sewing machine is stopped in a random position of the needle bar 5.

in order to withdraw the material being sewn from the stitch forming location and also for threading the needle 6, it is necessary, however, that the machine stops in a position that is remote from the material being sewn, more particularly about in its highest position. For this purpose the seamstress has to turn the manual lever 37 upwardly. If in this connection this lever is turned upwardly beyond its normal position in order to raise the presser foot 35 as shown in FIG. 4, the catcher 40 pushes itself from the cam 41 onto the abutment 42 of the switch bar guide 44 and thus displaces the same towards the left. By way of the switch bar 49 the angular lever 50 is turned about the stud 51 of the support 52 (FIG. 3), the arm 53 turns the transfer lever 55 against the force of the spring 59 about the bolt 56 of the support 52. Under the influence of the spring 64 which maintains the engagement of the housing 66 of the limit or end switch 62 against the abutment lug 67 the switch lever 60 is turned to the same extent about the bolt 56 until the shutoff member 68 rests against the abutment surface 15 of the rib [4 of the toothed belt disk 7 or against the abutment surface 16 of the segment member 11.

As the transfer lever 55 is turned further up to an end position determined by the dimension of the abutment 42 of the switch bar guide 44, the abutment lug 67 disengages itself from the housing 66 of the end switch 62 and the switch arm 58 releases the switch pin 65. The rest contact 77 of the end switch 62 is closed and the operating contact 76 is opened. The drive motor 34 now receives a partial potential picked up at the resistor 73 so that it drives the machine in the manner described above by way of belt disk 25 and the toothed belt disk 7, however at reduced speed.

As the toothed belt disk 7 rotates, the stop member 68 is guided against the segment member 11 by way of the flattened surface 17. The segment member 11 is pressed counter to the pressure of the torsion spring 3] against the end 12 of the rib l4, whereupon the stopping member 68 now drops into the disconnecting groove 69 which now presents its maximum width between the end 13 and the rib l4 and the segment member I]. In this position of the arm shaft 4, the needle bar 5 is in its highest position.

With this relative turning between the uncoupling ring it) and the toothed belt disk 7, the pin l8 takes along the clamping member 20 and releases its frictional connection with the bearing track 24. The coupling disk 22 and the belt disk 25 are uncoupled. By means of the stopping member 68 which has now entered, the toothed belt disk 7 and thus also the sewing tools are held in this position of the arm shaft.

As a result of the last rotational movement of the switch lever 60 connected with the stopping member 68 effected by the pull spring 59, the lever can again rotate relative to the transfer lever 55 which is in its end position until contact is made by the housing 66 of the end switch 62, with the abutment lug 67, while the switch arm 58 actuatesthe switch pin 65 of the end switch 62. The rest contact 77 of the end switch 62 is opened and the working contact 76 is closed, and thus the drive motor 34 is disconnected. The latter can run out owing to the uncoupling of the coupling disk 22 from the belt disk 25.

Upon turning back the manual lever 37, the pull spring 59 again pulls back the parts into their starting position.

With the pressure foot 35 lowered, the needle bar 5 may also be brought into its uppermost position. For this purpose the manual lever 37 is turned clockwise as seen in H0. 4. Thus, the catcher 40 presses against the abutment 43, slides the switch bar guide 44 to the left until engagement of the end 48 of the guide slot 45 at the bearing shaft 38, thereby initiating determination of the needle bar position in the manner described above without raising the presser bar 36. Upon release of the manual lever 37, it is pressed by the pull spring 59 acting on the switching bar 49 and the switch bar guide 44 into its initial position until engaging the end 48 of the guide slot 45 with the bearing shaft 38. With this, the stop member 68 swings out of the stop groove 69, the uncoupling ring is freed and turns under the bias of the torsion spring 3! until it engages the limiting abutment 30 against the screw 27.

Renewed actuating of the hand lever 37 against the abutment 43 of the switch bar guide 44 therefore efiects the driv ing of the machine by a further single turn, because as it is turned the stop member 68 contacts the abutment surface 16 of the segment member 1 l, and thus as in connection with the contact against the abutment surface of the rib 14 in the manner described above, the end switch 62 is raised from the switch arm 58 of the transfer lever 55 and thereby the closed circuit contact 77 of the end switch 62 is closed and the front 1 contact 76 is opened. Then the machine carries out a further shaft rotation. Thus by rhythmic actuating of the hand lever 37 against the abutment 43 of the switch bar guide 44 stitchby-stitch sewing can be carried out.

The winding is effected in the stop position of the machine, i.e. with the hand lever 37 raised to maximum height by actuating the starter. Thereby, the motor 34 merely drives the belt disk against which the winder (not shown) can be coupled, while the sewing mechanism is uncoupled.

Having now described the invention with reference to the embodiment illustrated, what we desire to protect by letters patent is set forth in the appended claims.

l claim:

1. In a sewing machine having a housing, a drive shaft in said housing, a needle bar operatively connected to one end of said drive shaft and supporting a needle, a presser foot bar proximate said needle bar, a belt disk and a coupling disk, an electric motor, a switch in a supply circuit connected to said motor, a belt connecting said belt disk to said motor, means for stopping said needle in a predetermined position, said means comprising a hand lever mounted proximate said presser foot bar, a switch lever having one arm supporting said switch and an arm presenting a shutoff member, a pivot supporting said switch lever on said housing, a transfer lever supported on said pivot having one arm operatively linked to said hand lever and an ann operatively disposed proximate said switch, an impeding or retarding device having an annular member mounted on said belt disk defining a gap and an uncoupling ring presenting a segment extending into said gap, said annular member and said segment presenting abutment surfaces for engagement by said shut off member, and a space between said segment and said annular member defining a groove adapted to receive said shutoff member, said transfer lever and said switch lever having proximate third arms and a spring biasing said third arms toward each other.

2. Means for stopping sewing machine needle bar and needle in a predetermined position as set forth in claim 1, including a supporting shaft pivotally supporting said hand lever on said housing for movement in opposite directions, said hand lever being operatively connected with said presser foot bar, a switch bar guide member linking said transfer lever to said hand lever and having a slot engaging said supporting shaft and having a pair of abutments and a catch associated with said shaft operative to engage said abutments and move said slide member in response to movement of said shaft.

3. Means in accordance with claim 2, including a free running clutch in said coupling disk having a clamping element defining an aperture, and a stud extending from said segment into engagement with said aperture.

4. In a sewing machine having a housing, a drive shaft in said housing, a needle bar operatively connected to one end of said drive shaft and supporting a needle, a presser foot bar proximate said needle bar, an electric motor, a switch in a supply circuit connected to said motor, a drive connection between said motor and said arm shaft, means for stopping said needle in a predetermined position; said means comprising a hand lever movably mounted on said housing, a switch lever having one arm supporting said switch and an arm presenting a shutoff member, a pivot supporting said switch lever on said housing, a transfer lever supported on said pivot having one arm operatively linked to said hand lever and an operating arm disposed proximate said switch, an impeding or retarding device comprising an annular member mounted in fixed position relative to said shaft and constituting an abutment surface having two ends defining a gap therebetween, and an uncoupling ring presenting a segment extending into said gap, said annular member and said segment presenting abutment surfaces for engagement by said shut off member, said transfer lever and said switch lever having proximate third arms, first spring means biasing said third arms toward each other operative to actuate said operating arm to open said switch, second spring means intermediate said housing and said third arm of said transfer lever holding said transfer lever in an end position and said shutoff member in a first position, said hand lever being linked to said transfer lever and operative to move said transfer lever to a second position to free said switch lever, move said shut off member into a position limited by said abutment surface and disengage said operating arm from said switch thereby closing the circuit of said motor until in a third position said shut off member enters said gap and said operating arm opens said switch.

5. Means for stopping a sewing machine needle bar and needle in a predetermined position as set forth in claim 4, including a supporting shaft pivotally supporting said hand lever on said housing for movement in opposite directions, said hand lever being operatively connected with said presser foot bar, a switch bar guide member linking said transfer lever to said hand lever and having a slot engaging said supporting shaft and having a pair of abutments and a catch associated with said shaft operative to engage said abutments and move said slide member in response to movement of said shaft.

Claims (5)

1. In a sewing machine having a housing, a drive shaft in said housing, a needle bar operatively connected to one end of said drive shaft and supporting a needle, a presser foot bar proximate said needle bar, a belt disk and a coupling disk, an electric motor, a switch in a supply circuit connected to said motor, A belt connecting said belt disk to said motor, means for stopping said needle in a predetermined position, said means comprising a hand lever mounted proximate said presser foot bar, a switch lever having one arm supporting said switch and an arm presenting a shutoff member, a pivot supporting said switch lever on said housing, a transfer lever supported on said pivot having one arm operatively linked to said hand lever and an arm operatively disposed proximate said switch, an impeding or retarding device having an annular member mounted on said belt disk defining a gap and an uncoupling ring presenting a segment extending into said gap, said annular member and said segment presenting abutment surfaces for engagement by said shut off member, and a space between said segment and said annular member defining a groove adapted to receive said shut off member, said transfer lever and said switch lever having proximate third arms and a spring biasing said third arms toward each other.

2. Means for stopping sewing machine needle bar and needle in a predetermined position as set forth in claim 1, including a supporting shaft pivotally supporting said hand lever on said housing for movement in opposite directions, said hand lever being operatively connected with said presser foot bar, a switch bar guide member linking said transfer lever to said hand lever and having a slot engaging said supporting shaft and having a pair of abutments and a catch associated with said shaft operative to engage said abutments and move said slide member in response to movement of said shaft.

3. Means in accordance with claim 2, including a free running clutch in said coupling disk having a clamping element defining an aperture, and a stud extending from said segment into engagement with said aperture.

4. In a sewing machine having a housing, a drive shaft in said housing, a needle bar operatively connected to one end of said drive shaft and supporting a needle, a presser foot bar proximate said needle bar, an electric motor, a switch in a supply circuit connected to said motor, a drive connection between said motor and said arm shaft, means for stopping said needle in a predetermined position; said means comprising a hand lever movably mounted on said housing, a switch lever having one arm supporting said switch and an arm presenting a shutoff member, a pivot supporting said switch lever on said housing, a transfer lever supported on said pivot having one arm operatively linked to said hand lever and an operating arm disposed proximate said switch, an impeding or retarding device comprising an annular member mounted in fixed position relative to said shaft and constituting an abutment surface having two ends defining a gap therebetween, and an uncoupling ring presenting a segment extending into said gap, said annular member and said segment presenting abutment surfaces for engagement by said shut off member, said transfer lever and said switch lever having proximate third arms, first spring means biasing said third arms toward each other operative to actuate said operating arm to open said switch, second spring means intermediate said housing and said third arm of said transfer lever holding said transfer lever in an end position and said shutoff member in a first position, said hand lever being linked to said transfer lever and operative to move said transfer lever to a second position to free said switch lever, move said shut off member into a position limited by said abutment surface and disengage said operating arm from said switch thereby closing the circuit of said motor until in a third position said shut off member enters said gap and said operating arm opens said switch.

5. Means for stopping a sewing machine needle bar and needle in a predetermined position as set forth in claim 4, including a supporting shaft pivotally supporting said hand lever on said housing for movement in opposite directions, said hand lever being operatively connected with said presser foot bar, a switch baR guide member linking said transfer lever to said hand lever and having a slot engaging said supporting shaft and having a pair of abutments and a catch associated with said shaft operative to engage said abutments and move said slide member in response to movement of said shaft.

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