US2741202A - Driving gear frame encased in shell section housing - Google Patents

Description

K. PFAFF April 10, 1956 DRIVING GEAR FRAME ENCASED IN SHELL SECTION HOUSING Filed May 17, 1952 United States Patent O DRIVING GEAR FRAM ENCASED IN SHELL SECTIN HOUSING Karl Pfat, Kaiserslautern, Germany, assigner to G. M. Pfa A.G., Kaiserslautern, Germany Application llay 17, 1952, Serial No. 288,43

3 Claims. (Cl. 1212-258) The invention relates to a sewing machine having a driving gear frame which is enclosed by shell sections. The shell sections which constitute the housing may be made of steel plate, die castings, plastic or other suitable moldable materials.

ln household sewing machines with electric drive the motor with the starter and components has been accommodated, for example, in a housing, the shells of which have been made in two parts permitting observation of the electrical connection after removing the front half or the housing. This housing was secured to the outside of the upper portion of the machine by means of a supporting arm.

It has also been proposed to enclose the motor and its component parts in the enclosure of the driving gear frame by disposing the electrical parts sidewise of the driving gear frame and by forming the enclosure as a laterally projecting, removable shell.

On the other hand, it has also been proposed to construct the upper portion of the sewing machine in the manner of a chassis and to enclose it by means of shells of metal plate, plastic or the like. In the known embodiments of this type, however, the chassis did not carry all necessary components for the operation of the sewing machine. The balance wheel was disposed outside the shells and also the illumination arrangement was not conlined within the shells enclosing the chassis. The power transmission means were likewise outside the shell portions which formed the housing of the sewing machine.

It is the purpose of the invention to undertake the encasing of the machine components including the driving gear frame in such a manner that the shell parts form a unitary structure which is closed with respect to the outside thus imparting to the sewing machine an attractive appearance. The invention solves this problem particularly in that the drive gear frame which is preferably constituted of a single member carries also the entire electrical fittings including motor, lighting device with connecting lead, socket to connect the supply line, socket to connect the starter and, as the case may be, transformer and switch for the lighting device, and that the entire installation is enclosed by shells in such a manner that a unitary structure is formed which is closed to the outside and without having noticeably protruding parts.

In accordance with the invention the upper and the lower parts of the driving gear frame with all machine components carried thereby are enclosed by three shell portions in a manner that the entire upper portion of the driving gear frame including the standard is encompassed by two shell portions.

The outer shell portion of the upper part and of the standard portion of the driving gear frame can be provided with a segment shaped cut-out to permit a portion of the hand or balance wheel to protrude. Furthermore, this shell portion along the standard section may have an aperture for the outwardly projecting lever on the elec- "ice trical motor which is pivotally supported on the driving gear frame, and movable by said lever against the force of a spring, and which transfers its torque to the balance wheel. The lever is also provided with a catch. Finally, 'this shell portion can also be provided with an aperture for inserting a spool which can be placed upon the end of the motor shaft which is formed as a spool carrier.

it is particularly advantageous that this construction permits the drive gear frame to be made as a single part. The production and particularly the mounting can now be effected in a clearly visible manner because all of the components required for the sewing operations are secured to the drive gear frame and are readily accessible and arranged in a manner to permit easy surveillance.

instead of providing'a socket for the connection of the starter it is also possible to install the starter directly upon the driving gear frame. In that case it is also possible to provide a knee lever in the well known manner by means of which the starter can be operated. Further features of the invention and details of the advantages provided by it will be apparent from the following description with reference to the appended drawings which schematically illustrates the embodiments of the shell enclosures for sewing machines in accordance with the invention.

Fig. l is a front view showing the driving gear frame and a cross section through the shells along lines I-I of Fig. 2;

Fig. 2 is a cross section along line'II-II of Fig. l;

Fig. 3 is a cross section along line III-III of Fig. 1;

Fig. 4 illustrates to an enlarged scale a partial cross section along line IV-IV of Fig. 2.

In the unitary drive gear frame the upper drive shaft 2 and the lower drive shaft 3 are supported in the well known manner. The connection between the two drive shafts is by means of a chain belt 4 which rests on gears S and 6. The upper drive shaft operates the needle shaft 9 and the thread take up lever 10 by way of the crank plate 7 and the intermediate link 8. The shuttle drive means 11 is connected in the known manner with the lower drive shaft 3. The hand or balance wheel 12 is arranged upon the upper drive shaft 2. The friction disc 13 of the motor 14 applies rotary movement to the hand wheel 12 and drives the machine.

The motor 14 is likewise pivotally related to the driving gear frame by a joint 15. A pull spring 16 which is also fastened to the driving gear frame applies the pressure between the friction disc 13 of the motor and the hand wheel 12 of the machine. The plug 17 for connecting thepower supply is directly fastened to the drive gear frame, as well as the socket 18 for connecting the adjustable starter switch, the sewing light 19 and its connecting lead 20, the low voltage transformer 21, as well as the push button switch 22 for the sewing light. The adjustable starter proper may be secured to the drive gear frame instead of having the socket 18 for plugging in the starter. In that event supports must be provided for an insertable knee lever by means of which the adjustable starter is operated in the known manner. It is here understood that the term adjustable starter switch refers to any motor current limiting device conventionally associated with a sewing machine such as a rheostat switch arranged for progressive actuation by either a human knee acting on an appropriately positioned lever or through the agency of well known foot treadle means. Where such rheostat is located remote from power supply plug 17, it must, of course, be connected in the circuit of motor 14 by some convenient means such as starter switch connecting socket 1S.

The drive gear frame 1 with all driving parts of the sewing machine and the components which form part of the electrical tittings in the conventional manner forms a chassis which is enclosed by shell sections 23, 24 and 25. The shell sections may be made from metal plate, as die castings, from plastics or similarmaterial. They impart an attractive appearance to the sewing machine. In the outer shell section 23 a cut out indicated at 26 is'provided throughrwhich the hand wheel 12 protrudes in the manner of a segment. vAll other parts of the chassis and of the electric ttings including the power transmission arrangement are inclosed by the sheils. A lever arm or catch bolt 27 having a boss or protuberancc 2S permits pivotally moving the motor against the force of the spring 16 in a manner that the boss 28 interlocks with an aperture 28a in shell section 23. The resulting oblique displacement of the motor permits the placing of a bobbin through the opening 29 upon the end Voli shaft 3 0 of the motor 14 which is in the orm of a bobbin shaft. In this manner it is also possible to prevent running of the machine while threading the bobbin. Upon removing the bobbin the motor can again be placed in operative position under the eect of spring 16 by raising lever 27.

Having now described my invention what I claim as new and desire to protect by Letters Patent is:

l. A sewing machine comprising a plurality of shells delining a housing and a unitary structure defining a driving gear frame supporting the driving gear including the balance wheel and the electrical ttings and leads to operate a sewing light and a starter switch connecting socket, said driving gear frame being a substantially U- shaped configuration and having a horizontal base p0rtion, a vertical standard portion and an upper horizontal arm portion and said shells forming a housing conforming to the U-shaped configuration of the driving gear irme and enclosing the same and the aforesaid elements thereon, and a motor with its shaft substantially parallel to the vertical standard portion of said frame and in driving engagement with the balance wheel, said vertical standard portion and said motor being disposed in the portion of said housing enclosing the vertical standard portion, said motor having a lever arm projecting outside said housing and said motortbeing pivotally supported for movement by said lever arm to disengage said balance wheel, and said lever arm having a protuberance adapted to interlock with said housing to maintain said motor disengaged from said balance wheel.

2. A sewing machine comprising a plurality of shells defining a housing and a unitary structure dening a driving gear frame supporting the driving gear including the balance wheel and the electrical iittings and leads to operate a sewing light and a starter switch connecting socket, said driving gear frame being of substantially U-shaped configuration and having a horizontal base portion, a vertical standard portion and an upper hori- Cir its said driving engagement with Vsaid balance wheel, one` end of the shaft of said motor having a conformation adapted to supporta bobbin and said `housing havingvan aperture and saidmshaftbeing in alignment with said v aperture to receive" a bobbin therethrough while said motor and said balance wheel aredisengaged. y v v 3. A sewing machine having a driving gear frame in the form of a unitary structurel supporting the complete mechanical driving gear including Vthe balance wheel and adapted to support the electrical equipment includinga motor, an electric light, connecting sockets, switcha starter switch connecting socket, transformer and con,-

nectng leads, said driving gear frame being of substantially U-shaped configuration and having a horizontal base portion,'a vertical standard portion and anvupper horizontal arm portion, said machine including a housing conforming to the U-shaped conguration of the driving gear frame and dei-ined by shells enclosing said frame and the components carried thereby, the upper outer shell having a cut-out portion'disposed around a protruding segment of the balance wheel and an aperture sidewise thereof, said motor being pivotally secured to the vertical standard portion of said frame with its shaft normally in a vertical position parallel to the vertical standard frame portion, spring means secured to said driving gear frame and said motor and arranged to hold said motor in driving engagement with the balance wheel,

v said motor having a lever arm extending through a slot deiined in said housing and said lever arm having a protuberance adapted to engage an edge of said slot to hold said motor in an inclined position in axial alignment with said aperture.

References Cited in the `tile of this patent UNITED STATES PATENTS 1,394,320 Mace Oct. 18, 1921 1,978,281 Pfat Oct. 23, 1934 2,430,932 Hohmann Nov. 1S, 1947 2,704,527 Theenhausen Mar. 22, 1955 FOREIGN PATENTS 240,607 Switzerland Apr. 1, 1946

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