US2739552A

US2739552A - Motor drives for sewing machines

Info

Publication number: US2739552A
Application number: US349163A
Authority: US
Inventors: Norris H Sailer
Original assignee: Singer Co
Current assignee: Singer Co
Priority date: 1953-04-16
Filing date: 1953-04-16
Publication date: 1956-03-27
Anticipated expiration: 1973-03-27

Description

. WITNESS March 27, 1956 N. H. SAILER 2,739,552

MOTOR DRIVES FOR SEWING MACHINES Filed April 16. 1953 2 Sheets-Sheet 1 INVENTOR. Q lamfiz's 6. daile'r ATTORNEY March 27, 1956 N. H. sAILER 9,5

7 MOTOR DRIVES FOR SEWING MACHINES Filed April 16, 1953 2 Sheets-Sha e: 2

- IN VEN TOR.

Q/Zmrm's 6 csailezr A] 'TORNEY United States Patent MOTOR DRIVES FOR SEWING MACHINES Norris H. Sailer, Union, N. J., assignor to The Singer Manufacturing Company, ElizabetlnN. J., a corporation of'New Jersey Application April 16, 1953, Serial No. 349,163

8 Claims. (Cl. 112-220 This invention relates to domestic or family type sewing machines and more particularly to a motor-drive arrangement, whereby a family or other type sewing machine may successfully be driven by an electric motor and control equipment which does not produce radio or television interference.

The conventional drive for family type sewing machines includes the use of a variable speed electric motor controlled by a speed regulating rheostat. Many of the variable speed electric motors now in use have carbon brushes contacting a rotating commutator. Also many of the speed regulating rheostats have carbon elements held together in such a manner that the pressure on the carbon elements may be varied to change the efiective resistance of the rheostat. Both the above described motor and speed controlling rheostat may on occasion cause radio and television interference and, thus, one of the primary objects of the present invention is to provide an improved motor drive for family type sewing machines which permits the use of equipment that in no way interferes with the use of radio or television receiving sets.

Another object of the present invention is to provide an improved motor drive arrangement capable of employing a constant speed induction type electric motor as a drive for a sewing machine.

Another object of the present invention is to provide an improved motor drive arrangement capable of employing a capacitor type electric motor as a drive for a sewing machine.

A further object of the present invention is to provide an improved starting and stopping mechanism for sewing machines in which the motor may be operated continuously and the sewing machine may be started and stopped without any electric sparking.

With the above and other objects in View, as will hereinafter appear, the invention comprises the devices, combinations and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention, from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

In the drawings:

Fig. 1 is an elevational end view, partly in section, of a portion of a family type sewing machine equipped with a motor drive embodying the present invention,

Fig. 2 is an elevational rear view, partly in section, of the sewing machine and drive shown in Fig. 1,

Fig. 3 is a fragmentary plan view taken substantially along the line 33 of Fig. 2,

Fig. 4 is a fragmentary sectional view in elevation taken substantially along the broken line 44 of Fig. 1,

Fig. 5 is a perspective view of certain parts shown in Figs. 1 and 2, and

Fig. 6 is a wiring diagram showing a modified form of connections.

The drawings, which form a part of this specification,

illustrate a sewing machine 10 mounted in a cabinet 11 by a pair of hinges, of which one is shown at 12. The cabinet includes, in addition to unshown elements, a vertical back 13, a vertical front 14, a vertical end 16, a vertical intermediate barrier 17, and a base 18. The sewing machine 10 includes in addition to a number of conventional unshown elements, a bed 19, a bracket-arm having an upright standard 21 supporting at its upper end a horizontally extending arm 22, said arm having a shaft 25. The bracket-arm rotatably supports a balance wheel 23 having a V-belt type driven pulley 24 formed integral therewith.

Preferably a motor which causes little or no radio or television inteference, for example, a constant speed induction type electric motor 26, which may, as shown, be a capacitor motor having a driving-end end bonnet 27 and another end-bonnet 28, is adjustably supported from the standard 21 by means of a bracket 29 which is formed integral with the end bonnet 27. To accomplish this, a screw 31, threaded into the standard 21, passes through a slotted hole 32 formed in the bracket 29. The motor 26 has a drive shaft 33 on the free end of which is mounted a drive pulley 34 having a groove 35 which is capable of receiving a V-belt. The lower right hand corner (Fig. l) of the end bonnet 27 is threaded as at 36 (Fig. 2) and thereby accommodates a threaded screw 37. The screw 37 pivotally supports one end of a lever 38 and rotatably supports a small-diameter grooved V-belt idler pulley 39. As best shown in Fig. 1, a driving V-belt 41 connects the balance wheel driven pulley 24 and the idler pulley 39, the

pulleys

24, 34 and 39 being of such size and so positioned that the V-belt 41 when stretched over the idler pulley 39 and the driven pulley 24 passes close to but does not actually make contact with the motor pulley 34, which latter pulley 34 is positioned intermediate the

pulleys

24 and 39 and between the two reaches 41 and 41 of the belt 41. In this connection it will be noted that the axes of the

pulleys

24, 34 and 39 are in a single plane designated by the letter P. Thus with the parts in the position shown by solid lines in Fig. 1 the motor 26 may be operated to drive the pulley 34 at full speed without the belt 41 or the balance wheel 23 of the sewing machine 10 being driven.

In order that the sewing machine 10 may be driven or stopped without stopping the motor 26, the lever 38 carries, at a location between the pivot screw 37 and its free end 42, a screw 43 which rotatably supports a disc shaped idler wheel 44. The free end 42 of the lever 38 is bent at an angle of degrees to provide an outwardly extending flange portion 46. Secured to this portion 46, by a pair of rivets 474'7, is one end of a cantilever leaf overload spring 48. The free end of the spring 48 carries a downfacing cup or contact member 49 of which the lower surface is concave as at 51 (Fig. 1) thereby to accommodate the upper substantially conical end of a knurled head 52. As best shown by solid and dotted lines in Fig. 1, the spring 48, the lever 38 and the idler wheel 44 may assume either a lowered or a raised position, upward movement thereof being limited by the contact member 49 engaging a stop 53 carried by the aforementioned bracket 29.

The knurled head 52 is adjustably screwed on the upper end of an upstanding push-rod 54; the desired adjusted position of the head 52 with respect to the rod 54 being maintained by a locking nut 56. The rod 54 passes through an opening 55 in the barrier 17 and the lower end of the rod 54 is pointed as at 57 and this point rests in a free concave end, or upfacing cup 58 of an arm 59 which is integral with and at an angle of 90 to a shaft 60. The shaft 60 is journaled in a support 62 which latter support is held to the cabinet base 18 by screws 63. The other end of the shaft 60 carries a member 64 journaled in the front wall 14 and which is held to the shaft 60 by a pin 66. The member 64 is entered by an end 69 of a knee-shift lever 72; the end 69 of the lever being anchored to the member 64 by a key 71. The knee-shift lever 72 is bent downwardly and on its depending end carries a knee pad 73. The shaft 60 and thus the knee pad 73 are biased to a desired position by a torsional spring 74 which is wound around the shaft 60.

In order to protect moving parts of the device, a shield 75 is placed around the

pulleys

34 and 39, the disc wheel 44, the lever 38 and the spring 48. This shield 75 is held to the motor 26 by screws 7676, and the shield has two openings, one opening 77 accommodating the V-belt 41, and the other opening 73 accommodating the knurled head 52.

Starting and control equipment for the electric motor is provided and as illustrated this includes a starting capacitor 81 having

terminals

82 and 83, a single-pole single-throw snap switch 84 having an operating handle 86 and

terminals

87 and 88, the capacitor 81 and switch 86 being mounted in a portion of the cabinet 11 defined by the wall 16 and barrier 17. A three conductor electric cord 89 connects the motor 26 with the switch 84 and the capacitor 81, while a two conductor electric cord 91 connects these items with a standard extension cord plug 92. As shown in Fig. 2, one of the conductors 93 of the cord 91 is connected to one of the conductors 94 of the cord 89. Also one conductor 96 of the cord 91 is connected to the switch terminal 87. The other two conductors 97 and 98 of the cord 89 respectively are connected to the terminals 8283 of the capacitor 81 and a jumper 99 connects the capacitor terminal 82 to the switch terminal 88.

The overload cantilever leaf spring 48 is an important feature of the present invention and is particularly useful for the following reasons. In the first place, the cross sectional dimensions of the V-belt 41 cannot be expected to be exactly the same at all points around the circumference of the belt. The spring 48 compensates for these variations in cross sectional dimensions and thus eliminates any pulsations in speed that would result from variations in belt dimensions. in the second place, the spring 48 and the stop 53 limit the pressure with which the operator can press the idler wheel 44 against the belt 41 and thus the pressure with which the belt 41 can be forced into the V-shaped groove 35 of the pulley 34. If this pressure were not limited, the operator could stall the motor 26 by jamming the belt 41 into the groove 35.

Operation With the parts in the position shown in Fig. 1 an operator places the plug 92 into an energized convenience outlet (not shown) and by moving the handle 86 closes the switch 84. This connects the motor 26 and the condenser 81 to the convenience outlet and starts the motor 26. Since the motor 26 and the starting condenser 81 do not have moving electric contacts that will produce sparking, starting the motor 26 does not cause radio or television interference. With the motor operating at full speed, the operator presses the knee pad 73 which moves the upfacing cup 58 and raises the push-rod 54. This raises the cantilever spring 48 which in turn pivots the lever 38 about the screw 37 until the idler wheel 44 contacts the outer surface of the V-belt 41. Further movement of the

parts

73, 59, 58, 54, 48 and 38 causes the idler wheel 44 to engage the outer surface of the belt 41 and to press the inner substantially V-shaped surface of the belt 41 into the groove 35 of the then rotating motor pulley 34. When this happens, the belt 41 is driven by the pulley 34 and the sewing machine balance wheel 23 is driven by the belt 41. Releasing pressure on the knee pad 73 allows the torsion spring '74 to lower the push-rod 54 with the result that the idler wheel 44 moves away from the belt 41 and the pulley 34, and

4 then the belt 41 becomes disengaged from the groove 35. This disconnects the motor from the sewing machine, which of course stops.

Modification As a modification and in addition to the hereinbefore described devices, a micro switch (Figs. 1, 3 and 6) is shown mounted on the barrier 17. This switch is of the type generally known as normally-open and has con tacts which close to establish an electric

circuit connecting terminals

121 and 122 whenever the operating lever 123 of the switch 120 is moved a fraction of an inch in the proper direction. To accomplish this, one end 124 (Fig. 3) of the spring 74 is extended beyond the arm 59, and the free end 125 of this spring is positioned just below the operating lever 123. Thus, whenever the knee-pad 73 is moved to turn the shaft 60 to begin to raise the arm 59 and the upfacing cup 58, the end 125 of the spring 74 will immediately raise the operating lever 123 to close the contacts (not shown) of the micro switch 120.

Fig. 6 is a wiring diagram of the modified form of the invention. This diagram shows that the connection between the

conductors

93 and 94 of Fig. 2 has been broken and that the micro switch 120 has been inserted therein. Thus, when the snap switch 84 and the micro switch 120 are both open, all electric energy is disconnected from the motor 26 and from the condenser 81. Also, since the micro switch 120 is under control of the knee pad 73, this switch 120 will open whenever the knee pad is completely released, as for example, when the operator leaves the sewing machine. On the other hand, since the micro switch 120 will close the instant pressure is applied to the knee pad 73, it will be understood that the operator will normally hold the switch 120 closed thus allowing the motor 26 to run continuously and that the operator will normally start and stop the sewing machine 10 by the hereinbefore described method of engaging and disengaging the V-belt 41 with the motor pulley 34. If the operator leaves the machine for an extended period, the snap switch 84 will be opened thus preventing inadvertent starting of the motor by accidentally contacting the knee pad 73.

While the herein disclosed belt shifting device has been shown associated with a capacitor type electric motor, it will be understood that other types of electric motors that do not cause radio and television interference may be used. For example, a three-phase squirrel cage induction motor could be used.

Having thus set forth the nature of the invention, what I claim herein is:

l. A motor driven sewing machine comprising; a bracket-arm having a standard; a balance wheel pulley rotatably supported by said bracket-arm; an electric motor supported by said sewing machine; a motor pulley mounted on and driven by said motor; an idler pulley supported by said sewing machine, said idler pulley being located on the side of the motor pulley which is remote from said balance wheel pulley and the axes of all three pulleys being substantially in the same plane; a belt stretched over said balance wheel pulley and said idler pulley and normally free from engagement with said motor pulley; and means for causing engagement of said belt and said motor pulley.

2. A motor driven sewing machine comprising; a bracket-arm having a standard; a balance wheel pulley rotatably supported by said bracket-arm; an electric motor; a switch for starting and stopping said motor, a motor pulley mounted on and driven by said motor; an idler pulley, said idler pulley being located on the side of the motor pulley which is remote from said balance wheel pulley and the axes of all three pulleys beingsubstantially in the same plane; a belt connecting said balance wheel pulley and said idler pulley and normally free from engagementwith said motor pulley; and means including a cantilever leaf spring for causing engagement of said belt and said motor pulley.

3. A motor driven sewing machine comprising; a bracket-arm having a standard; a balance wheel pulley rotatably supported by said bracket-arm; an electric motor; a switch for starting and stopping said motor; a motor pulley having a diameter that is smaller than the diameter of said balance wheel pulley; an idler pulley having a diameter that is smaller than the diameter of said motor pulley, said idler pulley being located on the side of the motor pulley which is remote from said balance wheel pulley and the axes of all three pulleys being substantially in the same plane; a belt connecting said balance wheel pulley and said idler pulley and normally free from engagement with said motor pulley; and means for causing engagement of said belt and said motor pulley.

4. A motor driven sewing machine comprising; a bracket-arm having an upright standard; a balance wheel pulley rotatably supported by said bracket-arm; an electric motor; a switch for starting and stopping said motor; a motor pulley having a diameter that is smaller than the diameter of said balance wheel pulley; an idler pulley having a diameter that is smaller than the diameter of said motor pulley, said idler pulley being located on the side of the motor pulley which is remote from said balance wheel pulley and the axes of all three pulleys being substantially in the same plane; a belt connecting said balance wheel pulley and said idler pulley and normally free from engagement with said motor pulley; a pivotally mounted lever; an idler wheel mounted on said lever and positioned adjacent to said belt; and manually operated means for moving said lever and thereby moving said idler wheel against said belt thus to move said belt into engagement with said motor pulley.

5. A motor driven sewing machine comprising; a bracket-arm having an upright standard; a large diameter balance wheel pulley rotatably supported by said bracketarm; a constant speed electric motor supported from said standard; a switch for starting and stopping said motor; a medium sized pulley mounted on and driven by said motor; a small diameter idler pulley mounted on said motor, said idler pulley being mounted on the side of the motor pulley which is remote from said balance wheel pulley and the axes of all three pulleys being in one plane; a belt connecting said balance wheel pulley and said idler pulley and normally free from engagement with said motor pulley; a lever pivotally supported on said motor; an idler wheel rotatably mounted on said lever; an upstanding push-rod having its upper end engaging said lever; and a manually operated member connected with said push-rod, thereby to force said belt into contact with said motor pulley.

6. A motor driven sewing machine comprising; a bracket-arm having an upright standard; a balance wheel V-belt pulley rotatably supported by said bracket-arm;

a constant speed capacitor-type electric motor supported from said standard; a switch for starting and stopping said motor; a V-belt motor pulley having a diameter that is smaller than the diameter of said balance wheel pulley mounted on and driven by said motor; a pivot screw carried by said motor; a V-belt idler pulley having a diameter that is smaller than the diameter of said motor pulley mounted on said pivot screw, said idler pulley being mounted on the side of the motor pulley which is remote from said balance wheel pulley and the axes of all three pulleys being in one plane; 'a V-belt connecting said balance wheel pulley and said idler pulley and normally free from engagement with said motor pulley; a lever pivotally supported on said pivot screw; 21 disc-shaped idler wheel rotatably mounted on said lever; a cantilever leaf spring carried by said lever; and operator controlled means for moving said leaf spring and thereby causing said idler wheel to move said belt into engagement with said motor pulley.

7. A motor driven sewing machine comprising; a bracket-arm having an upright standard; a large diameter balance wheel V-belt pulley rotatably supported by said bracket-arm; a constant speed capacitor-type induction electric motor supported from said standard; a switch for starting and stopping said motor; a medium sized V-belt pulley mounted on and driven by said motor; a pivot screw carried by said motor; a small diameter V-belt idler pulley mounted on said pivot screw, said idler pulley being disposed at the side of the motor pulley which is remote from said balance wheel pulley and the axes of all three pulleys being in one plane; a V-belt connecting said balance wheel pulley and said idler pulley and normally tree from engagement with said motor pulley; a lever pivotally supported on said pivot screw; a disc-shaped idler wheel rotatably mounted on the free end of said lever; a cantilever leaf spring carried on and extending beyond the free end of said lever; a downfacing cup carried on the free end of said cantilever spring; an upstanding push-rod having its upper end engaging said downfacing cup; a shaft supported from said cabinet and having an arm which at its free end carries an upfacing cup, said upfacing cup receiving the lower end of said push-rod; a torsional spring biasing said shaft in a direction to lower said upfacing cup and said push-rod; and a knee-shift lever carried by said shaft for turning said shaft against the torsional spring thereby to raise said push-rod and actuate said lever to force said disc-shaped idler wheel against the outer surface of said V-belt.

8. A sewing machine comprising a bracket-arm; a sewing machine shaft supported by said bracket-arm; an electric motor supported by said bracket-arm, and thereby forming a bracket-arm-motor combination; a driving shaft forming a part of said motor; a member completely supported by said bracket-arm-motor combination and adapted to be in driving relationship with one of said shafts and out of driving relationship with said other shaft; and a manually operable device supported by said bracketarm-motor combination, said device being movable to selectively establish and disestablish a driving connection between said member and the other of said shafts, thereby driving said sewing machine shaft from said motor shaft.

References Cited in the file of this patent UNITED STATES PATENTS 1,193,489 Welch Aug. 1, 1916 1,292,995 Beach Feb. 4, 1919 1,406,933 Cohn Feb. 14, 1922 1,488,234 Diehl et al Mar. 25, 1924 2,086,830 Thompson July 13, 1937 2,195,229 Smart Mar. 26, 1940 2,664,758 Smits Jan. 5, 1954 FOREIGN PATENTS 60,086 Switzerland Mar. 20, 1912 675,643 Germany Apr. 27, 1939