US2906222A

US2906222A - Start and stop motion mechanisms for sewing machines

Info

Publication number: US2906222A
Application number: US687657A
Authority: US
Inventors: Stanley J Ketterer; Michael F Ivanko
Original assignee: Singer Co
Current assignee: Singer Co
Priority date: 1957-10-02
Filing date: 1957-10-02
Publication date: 1959-09-29
Anticipated expiration: 1976-09-29
Also published as: GB897058A

Description

s. J. KETTERER EI'AL 2,906,222

Sept. 29, 1959 START STOP MOTION MECHANISMS FOR SEWING MACHINES Filed Oct. 2, 1957 2 Sheets-Sheet 1 Fig. I.

Sept. 29, 1959 5. J. KETTERER ETAI- 2 START AND STOP MOTION MECHANISMS FOR SEWING MACHINES Filed Oct. 2, 1957 2 Sheets-Sheet 2 INVENTORS. Y Stanley J. Keflerer and y v Michael F. Ivan/m ATTORNEY Unite START AND STOP MOTION MECHANISMS FOR SEWING MACHINES Application October 2, 1957, Serial No. 687,657

4 Claims. (Cl. 112-219) This invention relates to start and stop motion mechanisms for cyclically operated sewing machines, and more particularly to an improved control latch construction in a start and stop motion mechanism whereby the sewing machine may be maintained either in running, coasting or positively stopped position.

The control latch construction of this invention has particular utility in a start and stop motion mechanism of the type described in the US. patent application of Graham et al. Serial No. 660,779, filed May 22, 1957, in which the constantly moving driving vbelt of the sewing machine serves as a clutch element such that when the driving belt is compressed against a pulley face fast on the sewing machine main shaft, power will be transmitted to the sewing machine. 'With stop motion mech-. anisms of this type, the force required to shift the parts into running position increases sharply as the driving belt the stop motion mechanism in running position, the latch must be turned slightly beyond its normal running position in order to insure proper seating of the latch. With prior art latch devices ,the movement of the control latch slightly beyond its normal running position had to be accomplishedby the expenditure of excessive force on the part of the machine operator to overcome the ever increasing pressure needed to compress the driving belt beyond the point necessary to drive the sewing machine. In starting a start and stop motion device of this type, the .belt must be compressed beyond the point necessary to drive the sewing machine in order to assure proper seating of the latch which holds the start and stop motion device in running position.

It is an object of this invention to provide a control.

latch arrangement for a sewing machine start and stop motion mechanism having the driving belt serving as one part of a clutch means, in which latch arrangement the force required to be exerted by the sewing machine operator to start the sewing machine is not only materially reduced but also decreases as the driving belt is being compressed during the shifting of the latch into latchengaging position.

. With the above and other objects and advantages in view as will hereinafter appear, this invention comprises the devices, combinations, and arrangements of parts hereinafter described and illustrated in the accompanying drawings in which:

Fig. 1 represents a vertical cross sectional view of a portion of the bracket arm of a cyclic sewing'machine including the stop motion mechanism illustrated in stopped position and having this invention applied thereto, Fig. .2 represents an enlarged elevational view of portions of the stop motion mechanism of Fig. 1 illustrated in running position,'and

Fig. 3. is a diagrammatic view of the latch lever an Referring to Fig. 1, 11 indicates the bracket arm frame States atentO 2,906,222 Patented Sept. 29, 19 59 ice portion of a sewing machine in which is journaled a horizontal main shaft 12. All of the driven instrumentalities of the sewing machine are actuated by the main-shaft 12. but this invention is not concerned with the specific sewing instrumentalities of the machine and consequently, these have been omitted from the drawings. Reference may be had to the copending patent application of talities may be of any conventional construction.

j shaft and embraced by a connecting rod 15 adapted to drive a loop taker (not shown), and mechanismactw ated by the main-shaft for imparting endwise reciprocation to a needle bar (not shown).

Thestart and stop motion mechanism with which this 1 invention is concerned utilizes a continuously driven V belt 20 as a clutch element in the transmission of power from a motor (not shown), to the sewing machine main shaft. The belt travels on a composite pulley comprising a fast pulley side wall portion21 extending from a hub 22 secured for rotation with the main-shaft 12, and

a loose pulley portion journaled freely on the main-shaft and including a side Wall 23 and a bottom wall 24. The loose-pulley portion isfitted with a thrust bearing 25 engaged by a bearing finger 26 pivoted at the extremity of -a curved arm 27. The arm 27 isv rigidly secured to a is compressed. Where a control latch is used to hold stop motion frame 28 which is pivoted to the machine;

frame 11 by means of a fulcrum pin 29 carried in ears 30 formed on the machine frame. The stop motion frame. 28 includes an upward extension 31 which loosely embraces the main-shaft and has pivoted thereto a stop lever v 32 having a stop arm 33 projecting therefrom. The hub r. tion.

I 22 of the fast pulley portion is formed with a stop notch 34 into which the stop arm 33 can be seated to lock the sewing machine in a definite predetermined stopped'posia plunger-rod 35 journaled between its ends in a bearing lug 36 formed on the stop motion frame. A pair of recoil springs 3737 acting on the plunger rod, one at each side of the bearing lug'36, serve resiliently to center the plunger rod, thus to absorb the impact of a sudden stop and then to vreturn the stop arm and the main-shaft back -to' its predetermined stopped position. A coil spring 38 extending between the stop motion frame 28 and a stop motion control lever arm 49 serves to bias the stop motion frame into the stopped position as illustratedin Fig. 1. p

From the above description of the start and stop motion mechanism it will be understood that the operation of the machine is dictated by the position of the stop motion frame 28. Fig. 1 illustrates the position in which and the bearing finger 26 disengaged from the thrustbearingZS of the loose pulley so that the V belt 20 will ride idly on the bottom wall 24 of the loose pulley and will not frictionally engage the fast pulley side wall 21 to drive the machine. As the stop motion frame is initially moved counterclockwise as viewed in-the drawings, the stop arm 33 will be carried out of the stop notch to unlock the sewing machine. 'Th'emachine will then be in coasting position, i.e., free to turn but with the drive not yet established; Further-counterclockwise movement of the stop motion frame will bring the bearing finger into engagement with the thrust bearing 25 of the loosepulley and cause theloose pulley to move axially along the main-shaft toward Pivoted to the free extremity of the stop arm is the fast pulley side wall portion. In so doing, the V belt 20 will be compressed between the loose and fast pulley side wall portions and will ride up off the bottom wall of the loose pulley and into frictional driving relationship with the fast pulley side wall portion 21 as is illustrated in Fig. 2.

The mechanism for controlling the position of the stop motion frame 28 comprises a connecting link 40 pivoted at 41 to the stop motion frame and pivoted 'at 42 to a latch lever 43 which is fulcrumed on a shouldered screw 44 secured to the machine frame. A link 45 is hooked at one extremity through an aperture 46 in the latch lever 43 and at the other extremity through an aperture 47 in one arm 48 of an offset control lever fulcrumed on the stop motion frame fulcrum pin 29. The other arm 49 of the control lever may be actuated manually by any conventional foot treadle, or knee press.

One edge portion of the latch lever 43 is formed with a pair of spaced notches 50 and 51 which divide the edge portion of the latch lever into three portions of increasing

radius

52, 53 and 54. Playing over the notched edge portion of the latch lever is a pawl 55 pivoted on a fulcrum screw 56 secured in the machine frame and biased by means of a spring 57 into engagement with the latch lever 43. As the control lever arm 49 is depressed, the latch lever 43 will be turned in a counterclockwise direction by the link 45 and the connecting link 40 will transmit motion of the latch lever 43 to the stop motion frame 28. The pawl 55 moreover, in entering the notches 50 and 51 of the latch lever, will lock the stop motion frame against retrograde movement, the notch 51 corresponding to the coasting position in which the stop arm 33 is free of the stop notch 34 but in which the V belt has not yet established driving relation with the fast pulley, and the notch 50 corresponding to the running position of the machine as illustrated in Fig. 2.

Secured to the pawl 55 is a handle 60 by which the operator of the machine may trip' the pawl manually from the position shown in Fig. 2 in which the machine is running, first to the notch 51 in which the machine will coast, and then into the position shown in Fig. 1 in which the machine will be stopped in predetermined position of the main shaft 12.

The pawl 55 may also be tripped automatically in the same successive stages by suitable cam surfaces on the pattern cam which determines the cyclic operation of the machine. The automatic pawl tripping mechanism may be similar to that disclosed in the above referenced Graham et al. patent application Serial No. 660,779, filed May 22, 1957. In the accompanying drawings only a portion of the automatic pawl tripping mechanism is illustrated including a connection link 61 hooked through an aperture 62 in the pawl 55 at one extremity and pivoted at the other extremity to a rock arm 63 fast on a cam follower rock shaft 64 journaled vertically along the machine frame in a bearing bracket 65 and extending downwardly to the pattern cam.

As illustrated in Fig. 1 a conventional Work clamp opening shaft 66 is journaled in the machine frame. A rock arm 67 fast on the shaft 66 isengaged by a push rod 68 carried by a clamp opening lever 69 fulcrumed on the pin 23 which also carries the stop motion frame and the stop motion control lever. It is desirable in cyclic sewing machines to prevent opening of the work clamp when the machine is running and to prevent starting of the machine while the work clamp is opened. To this end, the rock arm 67 of the clamp opening mechanism is formed with aninterlock finger 70 and the stop motion latch lever 43 is formed with a shoulder 71 which is disposed when the machine is stopped as illustrated in Fig. l, at one side of the interlock finger 71 so that when the machine is stopped the work clamp may be opened. When the machine is running however, the shoulder 71 will lie in front of the interlock finger, as is illustrated in Fig. 2, and the work clamp opening mechanism cannot be operated. S1m1larly,

as illustrated in Fig. 1, if the work clamp is opened, the interlock finger 70 will be shifted in front of the shoulder 71 of the latch lever 43 and the stop motion mechanism will be locked so that the machine cannot be started until the clamp has been closed.

In starting the sewing machine described above, the major increment of force which the operator is called upon to supply is that necessary to compress the V belt 20 into proper frictional relationship with the fast pulley portion 21. The connecting link 40 interconnecting the latch lever with the stop motion frame may be adjusted as to length by means of a threaded connection 72 forming a part thereof and by the adjustment of the length of the rod, the degree of compression of the V belt in the final running position, shown in solid lines in Fig. 2, may be determined with great nicety. One of the disadvantages of prior art start and stop motion devices of this type has been that each time the machine is started a steadily increasing force was demanded of the operator in moving the stop motion lever from stop position to running position. Still another disadvantage was that in order to insure proper seating of the pawl into the notch in the latch lever, the latch lever must be turned a certain increment beyond the normal running position, and this additional turning movement in the prior art devices had to be accomplished in opposition to the highest forces acting to compress the V belt.

In this invention, the disadvantages of the prior art devices have been obviated. As illustrated in the drawings, the pivoted connection 42 of the connecting link 40 with the latch lever 43 has been positioned on the latch lever such that when the parts occupy positions corresponding to the running position of the stop motion mechanism, the connecting link 40, or more accurately a line joining the pivotal connections at each end of the connecting link, will extend substantially parallel to the radius from the latch lever fulcrum 44 of the point of connection 42 with the latch lever.

It will be understood that regardless of the shape of the connecting link 40, the link will impart or receive forces at the

pivotal connections

41 and 42 as if it extended in a straight line joining the pivotal connections. Hereafter, therefore, the term connecting link will refer to that link or its equivalent which extends in a straight line joining the pivotal connections.

In Fig. 3 line X-X represents the line joining the pivotal extremities of the connecting link 40 and the line R-- represents the radius of the point of connection 42 of the rod with the latch lever 43, the parts being disposed in the running position of the stop motion mechanism. Since the increment of motion imparted to the connecting rod for any increment of motion of the latch lever approaches zero as the lines X-X and R- approach parallelism, it will be appreciated that a two fold advantage is gained. First, the mechanical advantage of, the eifort applied to the connecting link by the latch lever increases sharply as the parts are moved toward the running position and, instead of an ever increasing force being required of the operator, a diminishing force is required instead. Second, in shifting the latch lever slightly beyond the running position in order to insure proper seating of the pawl, i.e., in moving to the dotted line position illustrated in Fig. 2, a minimum of additional compression of the V belt is occasioned and, therefore, the extra increment of force is not required of the operator.

The push rod 45 by which the latch lever is turned is preferably disposed such that the direction of force exerted by the push red, as indicated by line YY in Fig. 3, extends perpendicular to the radius R- of the point of connection 46 of the push rod on the latch lever. By this arrangement the machine operator may start the machine with exertion of the least possible force and, thus, operator fatigue is held to a minimum.

Having thus described the nature of the invention, what we claim herein is:

1. In a sewing machine start and stop motion mechanism having a frame means shiftable in one direction to start the sewing machine and in the opposite direction to stop the sewing machine, a latch lever fulcrumed on said sewing machine, means under control of the sewing machine operator for turning said latch lever, a connecting link pivoted to said frame means, and means pivoting said connecting link to said latch lever on a radius from the fulcrum of said latch lever which radius is substantially parallel to said connecting link when said frame means has been shifted to start the sewing machine.

2. In a start and stop motion mechanism for the acuating mechanism of a sewing machine of the type in which a portion of a pulley is fast with respect to the sewing machine actuating mechanism, and a driving belt serves as a clutch element in establishing driving relation between said belt and said fast pulley portion, a frame means shiftably supported with respect to said sewing machine for movement in one direction to force said belt into driving relationship with said fast pulley portion, a latch lever fulcrumed on said sewing machine, a connecting link pivoted to said frame means, and means pivoting said connecting link to said latch lever on a radius from the fulcrum of said latch lever which radius is substantially parallel to said connecting link when said frame means has been shifted to force said driving belt into driving relationship with said fast pulley portion.

3. In a sewing machine start and stop motion mechanism having a frame means shiftable in one direction to initiate running of the sewing machine and in the opposite direction to stop the sewing machine, means biasing said frame means in the direction to stop said sewing machine, a latch lever fulcrumed on said sewing machine, a connecting link pivoted to said a frame means, means pivoting said connecting link to said latch lever on a radius from the fulcrum of said latch lever which radius is substantially parallel to said connecting link when said frame means has been shifted to running position of the sewing machine, means under control of the sewing machine operator for turning said latch lever to initiate running of the sewing machine, and a pawl fulcrumed on said sewing machine and disposed in operative engagement with said latch lever to constrain said frame means in running position.

4. In a start and stop motion mechanism for the actuating mechanism of a sewing machine of the type in which a portion of a pulley isfast with respect to the sewing machine actuating mechanism, and a driving belt serves as a clutch element in establishing driving relation between said belt and said fast pulley portion, a frame means shiftably supported with respect to said sewing machine for movement in one direction to force said belt into driving relationship with said fast pulley portion, a latch lever fucrumed on said sewing machine, 2. connecting link pivoted to said frame means, means pivoting said connecting link to said latch lever on a radius from the fulcrum of said latch lever which radius is substantially parallel to said connecting link when said stop motion frame means has been shifted to force said driving belt into driving relationship with said fast pulley portion, a push rod under control of the sewing machine operator for turning said latch lever, and means pivoting said push rod to said latch lever on a radius from the fulcrum of said latch lever which is substantially perpendicular to said push rod when said frame means has been shifted to force said driving belt into driving relationship with said fast pulley portion.

References Cited in the file of this patent UNITED STATES PATENTS 329,753 Ludlow Nov. 3, 1885 2,721,526 Ivanko Oct. 25, 1955 2,825,296 Sweet et a1 Mar. 4, 1958