US2747040A

US2747040A - Stop-motion switch for sewing machine bobbin thread

Info

Publication number: US2747040A
Application number: US358823A
Authority: US
Inventors: Vossen Edward
Original assignee: Stop Motion Devices Corp
Current assignee: Stop Motion Devices Corp
Priority date: 1953-06-01
Filing date: 1953-06-01
Publication date: 1956-05-22
Anticipated expiration: 1973-05-22

Description

E. VOSSEN May 22, 1956 STOP-MOTION SWITCH FOR SEWING MACHINE BOBBIN THREAD Filed June 1, 1953 If, g a

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INVENTOR QM/P0 1/0555 QLMQ ATTORNEY United States Patent STOP-MOTION SWITCH FOR SEWING MACHINE BOBBIN THREAD Edward Vossen, Lynbrook, N. Y., assignor to Stepdviotien Devices Corp., Brooklyn, N. Y.

Application June 1, 1953, Serial No. 358,823

Claims. (Cl. 200---61.18)

This invention relates to a stop-motion switch for sewing machine bobbin thread.

Thread is fed to the needles of conventional sewing machines, used both in the home and in industry, from a spool or spools which are generally situated on or above the sewing machine, in plain view, and from a bobbin or a plurality of bobbins situated in or below the base of the machine, generally hidden from view. When the needle thread happens to break or terminate, that fact becomes almost immediately apparent to the operator of the machine but when a break occurs in the bobbin thread, or when the bobbin thread terminates, such event frequently escapes the attention of the operator until the machine has run a considerable time without the benefit of the bobbin thread.

This invention pertains solely and exclusively to the bobbin thread and the principal object of this invention is the provision of a stop-motion switch which is virtually instantaneously engaged and actuated by the needle thread immediately upon the severance or termination of the bobbin thread. It will be understood that this engagement of the switch by the needle thread takes place immediately above the presser foot of the machine, be-

ween its shank and the needle. In the normal operation of the machine, when all of the thread is continuous and unbroken, the needle thread will assume a substantially vertical position on the upward movement of the needle, between said needle and the presser foot. When the bobbin thread is severed or terminated, however, the needle thread will assume an angular position between the needle and the crook of the presser foot when the needle moves upwardly to its retracted position.

The foregoing is predicated upon the use of a presser foot made or modified as shown in the drawing and described in the specification. A conventional presser foot constructed without regard or relation to a stop-motion mechanism of the character described is provided with only a relatively small hole for the needle and needle thread. The small size of the needle hole in the presser foot prevents the needle thread from assuming an inclined position when the bobbin thread breaks or terminates. In the present invention, the needle hole in the presser foot is elongated in rearward direction and a rearwardly and downwardly sloping channel is formed in the bottom of the presser foot behind and in communication with said elongated needle hole. Consequently, when the needle thread is disengaged by the bobbin thread, it is enabled to assume an angular position behind the needle and through said elongated needle hole and sloping channel. It is this angularly positioned thread which engages the stop-motion switch herein described and claimed.

The stop-motion switch which comprises the present invention consists of two mechanisms which are associated with each other. The first is a trigger mechanism which is actuated by the angularly positioned needle thread. The second is a switch mechanism which is actuated by the trigger mechanism. In turn, the switch mechanism actuates the stop-motion mechanism which is adapted to disengage the sewing machine clutch. More precisely, when the bobbin thread breaks or terminates, the needle thread assumes its angular position and thereby engages and actuates the trigger mechanism. The trigger mechanism is set ofi or released and it engages and closes the switch mechanism. The circuit to the stop-motion mechanism is thereby closed and said stop-motion mechanism then operates to disengage the sewing machine clutch and to stop the operation of the sewing machine. The stopmotion mechanism may be conventional and it will neither be shown nor described herein.

Stop-motion switches which stop a sewing machine upon the breaking or termination of the bobbin thread are known to the prior art. It is important, however, that they operate as quickly as possible to prevent lengthy operation of the machine following the breaking of the bobbin thread or its termination. In the present invention, the stop-motion switch action is so fast that the machine is caused to stop before aflected area of the work passes the presser foot. No stop-motion switch mechanism known to the prior art is capable of functioning as quickly as the stop-motion switch mechanism herein described and claimed.

An important feature of this invention is the re-setting or cocking means which is associated with the trigger mechanism. This re-setting means consists simply of a small knob or similar handle which is provided with an arm that engages the trigger mechanism. When the knob is turned but a few degrees in one direction, it sets or cooks the trigger mechanism. When the bobbin thread breaks or terminates and the needle thread assumes its angular position to engage and release the trigger mechanism, the knob is automatically returned to its original position whence it may again be turned in the opposite direction to reset the trigger mechanism.

A preferred form of this invention is shown in the accompanying drawing in which:

Fig. 1 is a side view of a stop-motion switch for sewing machine bobbin thread, showing said switch mounted on the base plate of a sewing machine.

Fig. 2 is a top view thereof.

Fig. 3 is a front view.

Presser foot 10 shown in the drawing is a conventional sewing machine presser foot with the exception that it is provided with an elongated opening 12 for needle 14 and an inclined channel 16 at the rear of said needle opening and communicating therewith. Channel 16 slopes backwardly and downwardly from the needle opening in order to provide a relatively wide range of movement for the needle thread 18 in rearward direction at such time as it is disengaged from the bobbin thread when the latter is either broken or terminated. This elongated opening and the sloping channel which communicates with it are exaggerated in the drawing for purposes of clarity and it will be seen that they make it possible for the needle thread to assume its angular position indicated by the solid lines in Fig. 1 immediately upon the breaking or termination of the bobbin thread. interrupted lines 18a indicate the normal position of the needle thread when the bobbin thread is properly engaged thereby.

Also conventional is shank 25) which supports the presser foot on sewing machine base 22. The work 24 moves between the presser foot and plate 26 which is supported by said base. Mounted on the head 27 of the machine is housing 23 of stop-motion switch 33. The housing or casing may be entirely enclosed to protect the working parts of the switch but, again for purposes of clarity, it is shown in the drawing as an open casing. In one form of this invention, the casing has a top wall 32, a back wall 34, a front wall 36, a bottom wall 38, and a pair of

side walls

40 and 42 respectively. The front wall 36 is provided with an upwardly extending bar d4 which has a pair of aligned elongated holes 46 and 48 formed therein. Screws '50 projecting through said elongated holes secure bar 44 to the head 27 of the sewing machine and it is by this means that the entire stopmotion switch mechanism is mounted thereon.

The trigger mechanism of switch mechanism 30 is interposed, functionally, between the probe or feeler S2 and the switch proper. The probe is simply a wire or the like which has a laterally extending feeler portion 52.4, a longitudinally extending shank portion 52b, and a vertically extending back end portion 520' which is secured to a shaft 54. Shaft 54 projects through and is rotatably supported by side Wall 40 of the casing. It also projects through and is supported by side wall 42 of the casing and it is thereby provided with two bearing supports.

This shaft 54 carries an arm 56 securely fixed thereto. Spacers may be provided on said shaft between said arm 56 and the two side walls of the casing. Since arm 56 is fixed to "shaft 54 and since probe 52 is also fixed to said shaft, all three elements will move integrally with each other. Shaft 54 is free to turn about its own axis in its two side wall supports. When the bobbin thread breaks or terminates, the needle thread 18 will assume its angular position shown in Fig. l and it will engage probe 52 and cause said probe to pivot with shaft 54 and arm 56 about the axis of said shaft. It is this pivotal movementthat releases the trigger mechanism and actuates the switch.

A tension spring 58 is secured at one end to the inside of side wall 40 and at its opposite end to one end of arm 56. As viewed in Fig. 1, spring 58 acts to pivot arm 56 in clockwise direction. The opposite end of arm 56 is engageable with a shoulder 60 formed on slide '62. Slide 62 has a horizontally'extending portion 62a, a downwardly extending end portion 62b and a second horizontally extending portion "62c. Horizontal portion 62a is situated above and in parallel relation to horizontal portion 620. Horizontal portion 62a is the shorter of the two horizontal portions and on it is formed shoulder 60 above mentioned. The lower portion 62c is the longer of the two horizontal portions and it is slidably supported by yoke 64. This yoke is slotted at both ends to accommodate horizontal portion 620 and to enable said horizontal portion to slide horizontally of itself either forwardly or backwardly as thecase'may be. 'It will be seen that yoke 64 is provided with a downwardly extending side plate 66 which is secured by means of screws 68 to side wall 40 of the casing. Projecting downwardly from horizontal portion 62c, through an elongated-opening 70 in yoke 64, is a pin 72. Secured at one end to said pin .is a tension spring 74 and said tension spring is secured at its opposite end to side wall 40 of the casing. The action of spring 74 is to retract slide 62, that is, to pull it backwardly or leftwardly as viewed in Fig. 1.

An opening 76 is formed in the upper portion 62:: of slide 62. Projecting through said opening is an arm 78 secured to a shaft '30 which projects through and is rotatably supported by

side walls

40 and 42 of the casing. A knob 82 is secured to one outwardly projecting end of shaft 80. Knob 82 may be turned manually to the extent of only a few degrees in order to move slide 62 forwardly (rightwardly as viewed in Fig. 1) until shoulder 60 clears arm 56. Tension spring 58 will thereby be enabled to pivot arm 56 in clockwise direction as viewed in Fig. 1 until it engages shoulder 60. Knob 82 may now be released and slide 62 will be prevented from moving backwardly (leftwar'dly as viewed in Fig. 1) in response to the action of spring 74 thereon, since its shoulder 60 now abuts arm 56. The trigger mechanism, which cornpris'es arm 56 and spring 58 acting thereon and slide 62 and spring 74 acting thereon, is now cocked and ready for action.

When the bobbin thread breaks or comes to an end, needle thread 18 will assume its inclined Fig. 1 position and it will engage probe 52 and cause it to pivot slightly in counter-clockwise direction as viewed in Fig. 1. Since the probe is fixed to shaft 54 to which arm 56 is likewise a'tfixed, such pivotal movement of the probe will be reflected in a corresponding pivotal movement of arm 56. This will cause arm 56 to disengage shoulder 60 and slide 62 will thereupon be caused to slide leftwardly as viewed in Fig. 1 in response to the action of spring 74 thereon.

When slide 62 moves backwardly in response to the action of spring 74 (leftwardly as viewed in Fig. 1) its horizontal portion 620 will be caused to thrust switch arm in the direction of and into engagement with switch arm 92. Switch arm 90 is a leaf spring which is bowed to form a horizontal portion 901: and a vertical portion 90!) joined by a bight 900. The horizontal portion 90a is secured by means of bolt 94 to the top wall 32 of the casing. An insulating ,pad'96 prevents electrical contact between said horizontal portion 90a and the top wall of the casing. Bolt 94 also serves as a binding post or terminal and it is similarly insulated from the casing. An insulating pad 98 is secured to the vertical portion 9% of said contact member 90, on the side facing slide 62. Consequently,when slide 62 acts'upon contact 90 to thrust it leftwardly, there is no electrical engagement between said slide and said contact by reason of the presence of insulating pad 98.

Contact '92 may also be a leaf spring secured to wall 34 of the casing bymeans of bolt 1%. An insulating pad 162 is disposed between contact member 92 and said wall 34 of the casing to prevent electrical engagement thereb'etween. Bolt 1% "is also insulated from the casing and it may also serve as abinding post or terminal. Contact member '92 maybe bent upwardly at its lower end to provide a resilient contact portion 92a. When slide 62 pushes against insulating pad 98, contact member 90 flexes and is thrust into engagement with contact portion 92a of Contact 92 and the circuit to the stop-motion mechanism (not shown) is thereby closed and the stopmotion mechanism goes into operation to stop the machine. Contact 99 is normally biased away from contact 92.

The foregoing is illustrative of a preferred form of this invention and it will clearly be understood that this preferred form may be modified and other forms may be provided within the broad spirit and scope of the invention and the appended claims.

I claim:

1. A stop-motion switch for a sewing machine, comprising a casing, fastening means adapted to secure the casing to a sewing machine adjacent its presser foot, a probe pivotally mountedon said casing and adapted to project between said presser foot and the needle of said machine, a trigger mechanism in said casing connected to and actuated by said probe, and a switch mechanism in said casing which is connected to and actuated by said trigger mechanism, wherein the trigger mechanism corn prises apivotally movable arm and a longitudinally movable slide, both mounted in said casing, and each being engageable with the other, a spring connected to the pivotally mounted arm and tending to maintain said arm in engagement with the slide, and a second spring in engagement with the slide to thrust said slide in a predetermined direction relative to said arm when said arm is caused to disengage said slide against the action or the first mentioned spring.

. 2. A stop-motion switch for a sewing machine, comprising a casing, fastening means adapted to secure the casing to a sewing machine adjacent its presser foot, a probe pivotally mounted on said casing and adapted to project between said presser foot andthe needle of said machine, a -trigger mechanism in said casing connected to and actuated by said probe, and a switch mechanism in said casing which is connected to and actuated by said trigger mechanism, wherein the probe is fixed to a shaft which is-rotatably supported by the casing to enable said probe to pivot in either direction about the longitudinal axis of said shaft, and the trigger mechanism is connected to said shaft, said trigger mechanism comprising an arm which is fixed to said shaft and which is integrally movable with said shaft and with said probe, a movably mounted slide adjacent said arm, said arm being pivotally movable with said shaft and said probe into and out of engagement with said slide, a tension spring connected to said arm and urging it into engagement with said slide, and a second spring connected to said slide and urging it to move in a given direction against the action of said arm when said arm is in engagement with said slide.

.3. A stop-notion switch for a sewing machine, comprising a casing, fastening means adapted to secure the casing to a sewing machine adjacent its presser foot, a probe pivotally mounted on said casing and adapted to project between said presser foot and the needle of said machine, a trigger mechanism in said casing connected to and actuated by said probe, and a switch mechanism in said casing which is connected to and actuated by said trigger mechanism, wherein the switch mechanism com prises a fixed contact member and a movable contact member, both mounted within the casing, said movable contact member being movable into and out of engagement with the fixed contact member and being biased for movement out of engagement with said fixed contact member, a slide, said slide being mounted for engagement with the movable contact member, and for movement toward and away from the fixed contact member and urging said movable contact member to move in the direction of the fixed contact member to bring the movable contact member into engagement with the fixed contact member, means for manually retracting the slide against the action of said spring to release the movable contact member for biased movement out of engagement with the fixed contact member, a rotatably mounted shaft, an arm fixed to said shaft for pivotal movement into engagement with the slide to prevent movement of said slide in the direction of the fixed contact member and thereby to prevent engagement of the movable contact member with the fixed contact member, and second spring connected to said arm and acting to maintain it in engagement with said slide, said probe being also fixed to said shaft and being movable integrally therewith and with said arm, whereby actuation of the probe causes the arm to disengage the slide and the slide to move the movable contact member into engagement with the fixed contact member.

4. A stop-motion switch for a sewing machine, comprising a casing, fastening means adapted to secure the casing to a sewing machine adjacent its presser foot, a probe pivotally mounted on said casing and adapted to project between said presser foot and the needle of said machine, a trigger mechanism in said casing connected to and actuated by said probe, and a switch mechanism in said casing which is connected to and actuated by said trigger mechanism, wherein the trigger mechanism comprises a pivotally movable arm and a longitudinally movable slide, both mounted in said casing, each being movable in one direction to a position where it is out of engagement with the other and each being movable in the opposite direction to a position where it is engageable with the other, a spring connected to the pivotally movable arm and urging it in said opposite direction for engagement with the slide, a second spring connected to the slide and urging it in the first direction out of engagement with the pivotaliy movable arm, and manually actuated means connected to said slide for moving it in said opposite direction into engagement with the pivotally movable arm against the action of said second spring, both springs acting to maintain the arm and the slide in engagement with each other after the manually actuated means and the first mentioned spring have brought said arm and said slide into engagement with each other.

5. A stop-motion switch for a sewing machine, comprising a casing, fastening means adapted to secure the casing to a sewing machine adjacent its presser foot, a probe pivotally mounted on said casing and adapted to project between said presser foot and the needle of said machine, a trigger mechanism in said casing connected to and actuated by said probe, and a switch mechanism in said casing which is connected to and actuated by said trigger mechanism, wherein the trigger mechanism comprises a pivotally movable arm and a longitudinally movable slide, both mounted in said casing, each being movable in one direction to a position where it is out of engagement with the other each being movable in the opposite direction to a position where it is engageable with the other, a spring connected to the pivotally movable arm and urging it in said opposite direction for engagement with the slide, a second spring connected to the slide and urging it in the first direction out of engagement with the pivotally movable arm, and manually actuated means connected to said slide for moving it in said opposite direction into engagement with the pivotally movable arm against the action of said second spring, both springs acting to maintain the arm and the slide in engagement with each other after the manually actuated means and the first mentioned spring have brought said arm and said slide into engagement with each other, said switch mechanism comprising a fixed contact member and a movable contact member, both mounted within the casing, said movable contact member being movable into and out of engagement with the fixed contact memher and being biased for movement out of engagement with said fixed contact member, said movable contact member being situated adjacent said slide and being biased against the slide in opposition to the action of the second mentioned spring, whereby the slide thrusts the movable contact member into engagement with the fixed contact member when the slide is disengaged from the pivotally movable arm and is thrust in said first mentioned direction by the action of said second spring.

References Cited in the file of this patent UNITED STATES PATENTS 1,455,387 Cobb May 15, 1923 2,387,369 Vossen Oct. 23, 1945 2,387,958 Vossen Oct. 30, 1945 2,410,718 Crawford Nov. 5, 1946 2,643,305 Mansson June 23, 1953