US2337066A - Sewing machine - Google Patents

Description

Dec. 21, 1943. B. A. SCHMITT ETAL SEWING MACHINE Filed May l, 1939 2 Sheets-Sheet l Dec. 21, 1943. B A SCHMn-T ET AL 2,337,066

SEWING MACHINE Filed May l, 1939 2 Sheets-Sheet 2 Patented Dec. 21, 1943 SEWING MACHINE Bernard A. Schmitt and Allan A. Norin, Chicago,

lll., asslgnors to Sears, Roebuck and Co., Chicago, lll., a corporation of New York Application May 1, 1939, Serial No. 271,008

3 Claims.

This invention relates to mechanical movements, and is concerned more particularly with but is not limited to those pertaining to sewing machines.

It is an object of our invention to provide an vimproved drive between the motor shaft and the main shaft of a machine of th'e character referred to.

An additional object is to provide a drive of the character referred to exhibiting considerably reduced vibration.

It is another object to provide an improved motor speed and speed range control.

Another object is to provide an improved variable speed motor governor control.

A further object of our invention resides in the provision of a simplified and space-economizing feed dog drive enabling the motor to be attached, without crowding, on the bottom of a relatively small bed plate such as that employed on the domestic type of sewing machine.

Further objects and advantages of the invention will appear as the description proceeds.

Our invention will be better understood upon reference to the following description and accompanying two sheets of drawings, in which:

Fig. 1 is a fragmentary vertical longitudinal sectional view of a sewing machine embodying features of our invention and taken as indicated by the line I--I in Fig..3.

Fig. 2 is a fragmentary vertical sectional view taken as indicated by the line 2-2 in Fig. 1.

Fig. 3 is a bottom plan view taken as indicated by the line 3-3 in Fig. 1.

Fig. 4 is a fragmentary vertical cross-sectional view taken as indicated by the line 4-4 in Fig. 1.

Fig. 5 is an end elevation of the governor and control therefor appearing at the right in Fig. 3.

Fig. 6 is a bottom plan sectional View taken as indicated by the line 6-6 in Fig. 5.

Figi '7 is an inverted plan view showing a mechanism for actuating the governor control means.

Fig. 8 is a front sectional view, taken as indicated by the line 8-8 in Fig. 7 but showing the parts uninverted. A

Fig. 9 is a sectional elevation looking from the left to the right of the machine, taken as indicated by the line 9 9 in Fig. '7 but showing the parts uninverted.

Fig. 10 is similar to Fig. 7 but shows the mechanism in inoperative position.

Fig. 1l is an enlarged cross sectional view taken as indicated by the line Il-II in Fig. 2.

Fig. 12 is a longitudinal sectional view taken las, indicated by the line |2-I2 in Fig. l1.

Fig. 13 is a view similar to Fig. 12 but of a modiiled form of resilient drive.

Referring now more particularly to the drawings, the bed plate I5 may be hinged to a cabinet frame I6 by suitable means (not shown) as at the side Il thereof and preferably supports on the underside I8 thereof a motor I9 (Figs. 3 and 7), preferably driven at constant voltage from a suitable source of electricity (not shown). The motor has a shaft 20 carrying a worm 22 which drives a worm wheel 23 on a shaft 24. A second worm 28 on the shaft 24 has a 1 to 1 drive re- .lation to a second worm Wheel 21 mounted on a hook shaft 28 journaled in bearings 30.

The hook shaft supports a hook body 32 for rotation therewith. The body is provided with a loop seizing beak or hook 3| and the under thread is carried by a bobbin supported within a bobbin case 34 disposed Within the hook body and maintained against rotation therewthby means of a lug 42 on the bobbin case engaged within a recess 43 in a bar 44. The bar 44 may be suitably mounted as by a pin 46 and screw 41 on the bed plate.

The shaft 24 extends upward through an opening 48 in the bed plate and is journaled in bearings 49 which may be eccentric for adjustment purposes. A worm 50 about the upper end of the shaft 24 and capable of relative rotation is held against longitudinal movement by thrust collars 5I and 52, the latter having a hub to engage said worm. Resilient wires 53 securely held by the.l collar 52 and loosely received in sockets or bores 54 in the worm 50 establish a shock-absorbing drive between the collar 52 and said worm. Said worm drives a gear 55 on a main shaft 56 in the ratio of 1 to 2. Since the drive ratio between the worm 26 and the Worm wheel 2l is 1 to 1, it follows that the hook shaft 2B makes two revolu tions for each revolution of the main shaft 5E and hence for each cycle of the take-up 5l and needle 58.

The worm 50 could, of course, be fixed to the shaft 24, although the resilient drive is preferred for the reason noted.

The head or main shaft 56 carries an eccentric 60 mounted in a pitman 6| depending from the main shaft and pivotally connected at 62 to a crank 64 fixed as at E5 to a rock shaft B6 journaled in bearings 68 and mounted on the bed plate. The rock shaft 66 preferably extends longitudinally adjacent the rear side il of thebed plate.

Extending from the end of the shaft 55 opposite the crank 64 is a pair of arms 70 (Figs. 1,3 and 4) affording at their outer ends 7| bearings pivotally supporting a yoke 75. The yoke has arms 77 and 78 bridged by a bar 80.

The arm 77 may be formed with a channel 02 to slidably and adjustably receive a lug 83 formed on a feed dog 81|, said lug preferably havying a slot 85 through which a screw 87 passes to securely maintain the dog in the desired position of adjustment.

The eccentricity of the eccentric 60 is such as to impart oscillatory movement to the crank 50, thus causing the shaft 56 to rock, and, by means of the yoke 75, impart essentially horizontal reciprocatory movement to the feed dog 00.

Also disposed about the main shaft 55 is an eccentric mounted in a pitman 9| pivoted at 02 to a crank 53 xed as at 05 (Fig. 3) toa second rock shaft 05, suitably journaled in bearings 07, said shaft 95 running alongside the rock shaft 56. The shaft 50 extends to a point adjacent the yoke 75 and carries a crank |00 preferably fixed thereto as at |0|. A link |03 is pivoted as at |00 to the crank |00 and as at |05 to the yoke 75.

The eccentricity of the eccentric 90 is such that as the main shaft 55 rotates, tli crank 93 oscillates. rocking the shaft 95 and, through the crank |00, link |03 and yoke 75, imparting an essentially vertical reciprocation to the feed dog Itis thus apparent that the eccentric 50 imparts a generally horizontal reciprocation of the feed dog and the eccentric S0 imparts a generally vertical reciprocation to the feed dog. Thus the feed dog is influenced simultaneously by the eccentrics 60 and 50 and the path of its motion simulates a ilat oval, the dog completing one cycle for each revolution of the mein shaft 56.

As is clear from the foregoing` the hook shaft 28 rotates twice for every revolution of the main shaft 55 and cycle of the feed dog. The uniformity as well as the rate of rotation of the hook shaft is determined by the uniformity and rate of rotation of the motor shaft 20. Of each two revolutions of the hook shaft 28, one is a working revolution and the second is an idling revolution. The continuous rotation ofthe hook shaft 28 is verydesirable since a substantial amount of vibration inherent in other constructions wherein the hook shaft has interrupted rotation is avoided. Also, Joy virtue of the relationship of the shafts, cranks and associated parts, only a relatively short throw of the up-and-down feed is necessary, resulting in correspondingly reduced eccentric movement and vibration. All ofthe linkage at the bed plate is disposed on one side H0, leaving ample space on the other side for the mounting of the motor on the lower side of the bed plate without crowding.

A governor ||5 is mounted to rotate with the motor shaft 20 and carries a motor circuit closing means H5 comprising contacts ||7 and HB mounted on arms ||9 and |20 connected by springs |2| and |22 respectively to brackets |23. Pivotally connected at |20 to the base|25 of the governor H5 is a bell crank lever |26 having an arm |27 to which is pivotally connected as at |28 a link |20 havinga lug |30 engaged with the arm |20. The other arm |35 of the lever |25 may have a button |36 engageable with an end |38 of an arm |40 of a lever |5| pivoted at |02 to a bracket suitably mounted on the bed plate or other relatively stationary part. The lever |f|| has another arm |43, and either of its arms may be pressed by a spring |45 in a direction to cause the arm |40 to move the bell crank lever arm |35 away from the observer viewing Fig. 5, thereby urging the contact arm |20 away from the other contact arm I I9 and thus normally separating the contacts ||7 and ||3 and holding the motor circuit open.

It is evident that upon movement of the lever |0| against the action of the spring |05, i. e., toward the observer viewing Fig. 5, the spring |22 will be free to move the contact l5 into engagement with the contact ||7, so as to close the motor circuit and thereby operate the motor |9. The contacts ||7 and H5 are movable radially away from the axis of the motor shaft 20 in response to centrifugal force, which force, as to the Contact H7, is opposed by the spring |2| and, as to the contact H3, is opposed by the spring |05. 1t is evident that by altering the position of the lever arm |03, the position of the contact H5 and hence the motor speed at which the circuit will open is correspondingly controlled.

In accordance with our invention there is provided 'a governor control actuating mechanism within convenient access of the operator. Although various actuating mechanisms may be provided and adapted to be operated by foot, hand or otherwise, we prefer to provide such a mechanism which is under the control of a knee, as, for example, the right knee of the operator. To this end, we have provided a mechanism such as that appearing in Figs. 7 to 10. Said mechanism' may comprise a lever having a fixed pivot |5I. To one end of the lever |50 a link |53 is pivoted as at |50, the link |53 being guided between the frame or cabinet i0 and an oiset bracket |57 secured to the underside of the frame as at |50. The link |53 has at its free end a hook |50 providing a notch |5| into and out of which the curved end of the lever arm |05 readily slips as the bed plate I5 is swung down into and up out of operative position. A link |55 is pivoted at |05 to the link |53 and at |57 to a lever |50 pivoted at to the lever |50. The free end |72 of the lever |59 is received in a slot |70 in a manipulating lever lpivoted at |75 to a bell crank lever |77 pivoted at |50 to the frame |5. On the side of the pivot |80 opposite the pivot |75 the lever |77 is movably pivoted at |502 to a link |83 which is' in turn pivoted at |55 to the end of the lever |50 opposite the pivot |55.

The lever |75 preferably has a rounded free end bearing portion |86 projecting so that .its

convex side extends adjacent the right side of the right kneeof the operator, and also within easy reach of the right hand of the operator. As will be clear upon reference to Figs. 7 and 8, by moving the knee to the right and thus moving the lever end |86 to the right, as shown by the arrow |87 (Fig. '7), the bell crank lever |77 is swung about the fixed pivot |80 in a direction to draw the link |03 leftward, thereby actuating the lever |50 and link |53 in such manner as to swing the end |53 of the lever |0| to the right, i. e., toward the observer viewing Fig. 5, against the action of the spring |05, thereby'permitting the spring |22 to move the contact ||0 in to engagement with the contact ||7 so as to close the motor circuit and start the motor i9. As the motor speeds up, the contact I7 moves outward by centrifugal action. Since the outermost position of the contact H8 is controlled by the lever |4| which is in turn controlled by the operator through the lever |15, it follows that the operator determines and can vary within the ultimate limits of the device the speed at which the motor runs, the governor serving to hold the motor to any selected speed.` When the knee pressure on the lever end |86 is withdrawn, the spring |45 acts upon the lever |4| and, through such lever, upon the control linkage therefor to return the various parts to the positions shown in Fig. 5.

Itis advisable but not absolutely necessary to withdraw the hook |60 to some such position as that shown in Fig. when the bed plate -is to be raised or lowered. In the previous operation of the control linkage for the lever lli, the vlink |65 and lever |69 play no part. For the purpose of moving the hook |60 out of and into the position shown in Fig. 7, the link |65 and lever |69 are utilized. For this purpose the operator grasps the lever end |86 in her hand and swings it rearward about the pivot |16, as shown by the arrow I 80, thereby swinging the lever |60 forward about the pivot |10, and thus, through the link |65, swinging the hook I 6 0 forward as shown by the arrow |60. By a reverse swinging of the lever end |66, the hook |63 may be restored to the position shown in Fig. 7,

spring 208. 'lhe worm preferably has an extension 209 projecting within the upper end of the spring. the extension 2|0 on the lower collar 205 serving as a stop to limit downward movement of the worm and ttlng in the lower end of the spring, whereby to retain the spring' in proper position. The collars 200 and 205 are preferably molded of phenolic condensation product or other suitable preferably non-metallic material so that the engagements'between the worm and the collars will be noiseless or substantially so.

Various modiications may suggest themselves to those skilled in the art without departing from the spirit of our invention, and, hence, we do not wish to be restricted to the specific form shown or'uses mentioned, except to the extent indicated in the appended claims, which are to be inter- When the parts are arranged as shown in Fig.

including shafting disposed at one side of the' hook shaft, leaving ample space for the motor without crowding and thus requiring a substantially smaller bed plate than has heretofore been necessary for a machine of comparable size. Also we have provided an eiiicient motor speed control at all times under the control of the operator and which enables the operator to run the motor at any desired speed, the control being adapted to be rendered inoperative whereby to preclude accidental operation of the motor when it is plugged in for electricity.

Of course thewires couldbexedin theworrn Y Il and loose in the collar 62 ifdesired.

Another form of shock-absorbing drive is shown in Fig. 13. This arrangement includes the shaft 24, an upper collar 200 ilxed at 20| to the shaft, a worm 202 longitudinally slidable on the shaft end keyedas at 204 thereto so as to rotate therewith,- a lower collar 200 suitably xed to the shaft as at 206, and. a coil orother suitable spring or other resilient member 200 between the worm and the collar 200, constantly urging the worm against the collar 200. Whenexcessive resistance is oilered to the drive, the rotation of the shaft 2l is not interrupted, but, instead, the worm wheel I6 exerts a reactive camming force on the worm 202, camming the latter downward along preted as broadly as the state of the art will permit.

We claim:

1. In a device of the class described including a frame, a sewing machine carried thereby and including a. swingably mounted bed plate, and a motor for said machine; a motor control carried by said bed plate and comprising a member movable to vary the speed of the motor, means comprising an element mounted at the underside of said frame 'and movable in one direction by a knee of the operator seated at the machine for moving said member, and means operative in response to a. different movement of said element for rendering said member non-responsive to knee operation.

2. In a device of the class described including a sewing machine, a motor therefor, and a motor control comprising a member movable to vary the speed of the motor; an arm connectible with and disconnectible from said member, means operatively connected with said arm and arranged to be moved by a knee of an operator seated at the machine to move said member when said arm is connected to said member, said means being operative 4to disconnect said arm from said mem` ber so as to render said member non-responsive to' knee action, whereby accidental operation of said member by the knee is obviated.

3. In a device of the class described including a sewing machine. a motor therefor, and a motor control comprising a membermovable to vary the speed ot the motor; an arm connectible with and disconnectible from said member, means operatively connected with said arm and arranged to be moved by a knee of an operator seated at the machine to move said member when said arm is connected to said member, said means being operative to disconnect said arm from said member so as to render said member non-responsive to knee action, whereby accidental operation of said member by the knee is obviated. said arm being mounted to actuate said member only when the knee is moved sidewise, said arm being movable to disconnected position in response to a manual pull by the operator upon said means.

the shaft notwithstanding the resistance of the Y BERNARD A. SCHMITT. ALLAN A, NORIN.

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