US2516156A - Speed governor for sewing machine motors - Google Patents

Description

y ,5 c. H. SPARKLIN 2,516,156

SPEED GOVERNOR FOR SEWING MACHINE MOTORS Filed July 20, 1945 2 Sheets-Sheet 1 July 25, 1950 c. H. SPARKLIN 2,515,156

SPEED GOVERNOR FOR SEWING MACHINE MOTORS Filed July 20, 1945 2 Sheets-Sheet 2 Patented July 25, 1950 SPEED GOVERNOR FOR SEWING MACHINE MOTOR Charles H. Spar-kiln, Chicago, Ill., assignor to Birtman Electric Company, a corporation of Illinois Application July 20, 1945, Serial No. 606,076

7 Claims.

on small motors, like a'sewing machine motor.

They are inefilcient over a wide range of speed values, and the range over which they operate is oftentimes not great enough to give the desired broad range.

I have invented a speed control for sewing machine motors that is efllcient over a wide range of speeds, yet is simple in construction and light in weight. This new apparatus is small, so that it can iltinto a limited space, and is provided with means for easily changing the speed of the motor. The new and improved speed control includes the speed governor and means for varying the operation of the governor at a remote point. The new control is especially adaptable for sewing machine motors in that it is light in weight, of mall construction, and is equally efficient over a wide range of speed values.

The invention will be described as related to the embodiment set out in the accompanying drawings. of the drawings, Fig. 1 is an elevation partially broken away, showing the new speed control for a sewing machine motor; Fig. 2 is a view taken along line 2--2 of Fig. 1; Fig. 3 is an elevation, partially in section, of a sewing machine motor and attached speed governor; Fig. 4 is a section taken along line I of Fig. 3; Fig. 5 is a section taken along line 5 of Fig. 3; and Fig. i5 is a section taken along line 6-8 of Fig. 4.

The speed control includes a speed governor in mounted adjacent a sewing machine motor I i. The governor and motor are preferably of the same diameter, so that one appears to be merely an extension of the other, as shown in Figs. 1 and 3. The motor H has a shaft l2, on one end or which is mounted a friction wheel l3 for operating the drive wheel ll of a sewing machine It. The speed governor it, which is shown mounted on the opposite end of the motor, is preferably constructed like the speed governor set out in my copending application Serial No. 580,114, filed February 28, 1945. A full and complete description of the speed governor is given in the application cited hereinabove.

The end of the motor shaft l2 opposite the 2 end upon which the flange wheel I! is mounted extends beyond the motor. Upon this end of the shaft is mounted a pair of parallel plates i6 arranged for rotation with the shaft. These plates are held in their parallel relationship by means of a plurality of studs l'l passing through the plates. On two of these studs there are located a pair of centrifugally responsive arms l8, fulcrumed at one end. As the plates i6 rotate, these arms move outward under the action of centrifugal force. Bearing against these arms are two bell cranks i9 arranged so that both legs of each bell crank lie substantially within the confines of the rotatable plates IS. These bell cranks are arranged so that each arm I8 bears against one leg of the bell crank as the arms move outward under centrifugal force. Each non-contacting leg of the bell cranks bears against a second bell crank 20 mounted on the plates l6 and substantially at right angles thereto. The free ends of the second bell cranks 20 extend toward the shaft i2 and are in contact with the bottom of a slideable cylinder 2i mounted on the shaft l2.

The end of the slideable cylinder 2|, which is opposite the rotatable plates, passes through a hole 22 in one arm 23 of a contact switch 24, and pushes against a bearing piece 25 on the other switch arm 25.

The switch 24 is held closed by means of a spring 21 operating on the two parallel arms of the switch. These switch arms are mounted for rotation around a fulcrum 28, and the spring 21 is preferably located at this point. The contact point 29 are held in closed position by means of this fixed spring 27, and the bearing piece 25 is held against the slideable cylinder 2| by means of a variable spring 30.

The switch arm 23, through which the slideable cylinder 2! passes, has an extension 3i extending beyond the fulcrum 28, around which the switch is mounted for movement. A bearing member 32 presse against the end of the extension 3| and serves to position the switch about its fulcrum. This bearing member 32 is provided with screw threads 33 that mesh with screw threads in a fixed mounting 34. The bearing member 32 extends beyond the fixed mounting and has a smooth end bearing against the switch arm extension 3l. The other end of the bearing memher is finished in a flat plate 35. Attached to the fixed mounting 34 at the end opposite the bearing member is a flexible cable 36, mounted for axial rotation. This cable is attached to a fitting i'l extending into the mounting and terminating in a cylindrical member 38 which has an axial groove 39 at its inner end for engagement with the flat plate 35. This construction is provided so that as the cable 36 is revolved the end fitting 31 turns the bearing member 32 and screws it in and out of the fixed mounting 34, thereby moving thefiat plate back and forth in the groove 39. i

The flexible cable 36 extends to a point remote from the speed control and the motor. At this end of the cable there is positioned a pinion gear 40, which is engaged by a toothed sector 4|. This toothed sector 4| forms a part of an arm 42 mounted for rotation around a fulcrum 43. In the construction shown the pinion gear 40 is mounted on a flat plate 44 that is attached to the underside of a table 45, upon which the sewing machine, motor, and speed governor are mounted. This flat plate 44 is arranged vertically by being attached to a vertical side of the table. A second flat plate 46 is arranged parallel to the first plate 44 and spaced therefrom. The end of the flexible cable 35 passes through this second plate 46, and the pinion gear 40 is located between the plates. .The arm 42, which forms an extension of the toothed sector 4|, is of a generally semicircular shape, with the toothed sector at one end and the fulcrum 43 at the opposite end. Mounted on this armin adownwardly extending position is a lever 41 for operating the control mechanism. This lever is bolted at one end through a slot 48 provided in the arm 42 so that it can be readily positioned in the slot by thumb screw 49. In order to limit movement of the arm 42 there is provided a stud 50 extending through an arcuate slot in the second flat plate 46. The curved arm 42 is held in a position corresponding to slow motor speed by means of a spring 52 attached to the arm and to the second flat plate 46.

When the speed control is set for any given speed the rotatable plates I6 rotate with the motor shaft l2.- This causes the movable arms l8 to move outwardly under the influence of centrifugal force set up in these arms. speed increases these arms l8 move out further under the increased centrifugal force. This movement causes bell cranks I! to move about When the their fulcrums and operate second bell cranks 20.

The free arms of the second bell cranks push out on the cylindrical fitting 2|, and when the speed becomes great enough, pushes switch arm 25 away from switch arm 23, and breaks the electrical circuit to the motor by separating the contact points 29. The contact points are held in normally contacting relationship by means of the fixed spring 21 and the variable spring 30. The structure and purpose of these two springs are set out in detail in my copending application cited hereinabove.

When it is desired to change the setting of the speed control the operator of the sewing machine moves lever 41 with her knee. This causes the toothed sector 4| to locate the flexible cable 36 and position the bearing member 32 within its fixed mounting 34. The position of the bearing member bears against the extension 3| to the first switch arm 23, and thereby determines the position of the switch 24 relative to the rotatable plates it. As can be seen, this relative position of the switch is what determines the speed at which the motor operates. Whenever it is desired to change the speed of the motor, it is only necessary to move the lever 41.

From the foregoing description it can be seen that the speed control is readily adjustable to provide any speed desired over the operating range. This operating range in one installation set out in my copending application is from 618 R. P. M. to 6790 R. P. M.

This invention has been described in considerable detail as related to one embodiment of the same. It is to be understood, however, that the invention is not to be limited by these details unless otherwise specified, but rather be construed broadly within its spirit and scope as set out in the accompanying claims.

I claim:

l. A speed control comprising a rotatable member arranged for rotation in a substantially fixed plane, means for rotating said member, an electric switch mounted on a fulcrum for ready movement to position said switch relative to said rotatable member, said switch including an arm extending beyond the fulcrum, means operable by the rotation of said rotatable member for breaking contact of said switch when the speed of rotation exceeds a predetermined value, with this predetermined speed being dependent upon the position of the switch relative to the rotatable member, a threaded bearing member bearing against said extended switch arm and held in a similarly threaded fixed mounting, a flexible cable leading from the bearing member to a point remote from the speed control, a pinion'gear mounted on the end of the flexible cable, a toothed sector in engagement with the pinion gear with the sector forming a part of an arm mounted on a fulcrum, and means urging said sector arm toward a low speed position.

2. A speed control comprising a rotatable member arranged for rotation in a substantially fixed plane, means for rotating said member, an electric switch mounted on a fulcrum for ready movement to position said switch relative to said rotatable member, said switch including an arm extending beyond the fulcrum, means operable by the rotation of said rotatable member for breaking contact of said switch when the speed of rotation exceeds a predetermined value, with this predetermined speed being dependent upon the position of the switch relative to the rotatable member, a threaded bearing member bearing against said extended switch arm and held in a similarly threaded fixed mounting, a flexible cable leading from the bearing member to a point remote from the speed control, a pinion gear mounted on the end of the flexible cable, a toothed sector in engagement with the pinion gear with the sector forming a part of an arm mounted on a fulcrum, and a lever rigidly fixed to the arm for movement thereof about the fulcrum.

3. A speed control comprising a rotatable member arranged for rotation in a substantially fixed plane, means for rotating said member, an electric switch mounted on a fulcrum for ready movement to position said switch relative to said rotatable member, said switch including an arm ex tending beyond the fulcrum, means operable by the rotation of said rotatable member for breaksector in engagement with the pinion gear with the sector forming a part of an arm mounted on a fulcrum, and a lever fixed to the arm for movement thereof about the fulcrum, the pitch diameter of the toothed sector being considerably greater than the pitch diameter of the pinion gear so that twist effect of the flexible cable is negligible.

4. A speed control comprising a rotatable member, means for rotating said member, an electric switch comprising a pair of arms arranged side by side spaced from therotatable member and arranged approximately at right angles to the axis of rotation of the rotatable member, said arms having cooperating contact members at one of the ends of the arms and being mounted for rotational movement about a fulcrum at the other ends of the arms, with said movement being toward and away from the rotatable member, means operable by rotation of said rotatable member for breaking contact between said contact members when the speed of rotation of the rotatable member exceeds a predetermined value with said value being dependent upon the distance between the switch and the rotatable member, an arm forming a part of said switch and extending beyond the fulcrum, a bearing member normally contacting said arm and having at least a portion of its surface threaded, a fixed mounting member in which the bearing member is held with the mounting member having similar threads engaging those of the bearing member, a flexible cable leading to a point remote from the bearing member and being attached to the bearing meber to rotate it when said cable is rotated about its axis, a pinion gear mounted on the end of the cable and fixed for rotation about an axis coinciding with the axis of the cable, a sector arm mounted for rotation about a fulcrum at one end having teeth on its opposite end engaging the pinion gear, said teeth being located on the arc of a circle whose center is substantially at the fulcrum, and a. second arm having one end rigidly fixed to the sector arm and extending away from the sector arm.

5. A speed control comprising a rotatable member, means for rotating said member, an electric switch comprising a pair of arms arranged side by side spaced from the rotatable member and arranged approximately at right angles to the axis of rotation of the rotatable member, said arms having cooperating contact members at one of the ends of the arms and being mounted for rotational movement about a fulcrum at the other ends of the arms, with said movement being toward and away from the rotatable member, means operable by rotation of said rotatable member for breaking contact between said contact members when the speed of rotation of the rotatable member exceeds a predetermined value with said value being dependent upon the distance between the switch and the rotatable member, an arm forming a part of said switch and extending beyond the fulcrum, a bearing member normally contacting said arm and having at least a portion of its surface threaded, a fixed mounting member in which the bearing member is held with the mounting member having similar threads engaging those of the bearing member, a flexible cable leading to a point remote from the bearing member and being attached to the bearing member to rotate it when said cable is rotated about lts axis, a pinion gear mounted on the end of the cable and fixed for rotation about an axis coinciding with the axis of the cable, a sector arm mounted for rotation about a fulcrum at one end and having teeth on its opposite end engaging the pinion gear, said teeth being located on the arc of a circle whose center is substantially at the fulcrum, and a second arm having one end rigidly fixed to the sector arm and extending away from the sector arm, said second arm being attached to the sector arm at a point between the fulcrum end and the teeth end.

6. A speed control comprising a rotatable member, means for rotating said member, an electric switch comprising a pair of arms arranged side by side spaced from the rotatable member and arranged approximately at right angles to the axis of rotation of the rotatable member, said arms having cooperating contact members at one of the ends of the arms and being mounted for rotational movement about a fulcrum at the other ends of the arms, with said movement being toward and away from the rotatable member, means operable by rotation of said rotatable member for breaking contact between said contact members when the speed of rotation of the rotatable member exceeds a predetermined value with said value being dependent upon the distance between the switch and the rotatable member, an arm forming a part of said switch and extending beyond the fulcrum, a bearing member normally contacting said arm and having at least a portion of its surface threaded, a fixed mounting member in which the bearing member is held with the mounting member having similar threads engaging those of the bearing member, a flexible cable leading to a point remote from the bearing member and being attached to the bearing member to rotate it when said cable is rotated about its axis, a pinion gear mounted on the end of the cable and fixed for rotation about an axis coinciding with the axis of the cable, a sector arm mounted for rotation about a fulcrum at one end having teeth on its opposite end engaging the pinion gear, said teeth being located on the arc ot'a circle whose center is substantially at the fulcrum, and a second arm having one end rigidly fixed to the sector arm and extending away from the sector arm, said second arm being attachable to the sector arm at any one of a plurality of points between the fulcrum end and the teeth end.

7. A speed control comprising a rotatable member, means for rotating said member, an electric switch comprising a pair of arms arranged side by side spaced from the rotatable member and arranged approximately at right angles to the axis of rotation of the rotatable member, said arms having cooperating contact members at one of the ends of the arms and being mounted for rotational movement about a fulcrum at the other ends of the arms, with said movement being toward and away from the rotatable member, means operable by rotation of said rotatable member for breaking contact between said contact members when the speed of rotation of the rotatable member exceeds a predetermined value with said value being dependent upon the distance between the switch and the rotatable member,

an arm forming a part of said switch and extending beyond the fulcrum, a bearing member normally contacting said arm and having at least a portion of its surface threaded, a fixed mounting member in which the bearing member is held with the mounting member having similar threads engaging those of the bearing member, a flexible cable leading to a point remote from the bearing member and being attached to the bearing member to rotate it when said cable is rotated about its axis, a pinion gear mounted on the end of the cable and fixed for rotation about an axis coinciding with the axis of the cable, a sector arm mounted for rotation about a fulcrum at one end having teeth on its opposite .end engaging the pinion gear, said teeth being located on the arc of a circle whose center is substantially at the fulcrum, and a second arm having one end rigidly fixed to the sector arm and extending away from the sector arm, said second arm being attachable to the sector arm at any one of a plurality of points between the fulcrum end and the teeth end, and means for urging the sector arm toward a low speed position when no force is applied to said second arm.

CHARLES H. SPARKLIN.

REFERENCES CITED The following references are of record in the file of this patent:

Number Number 15 7,276

8 UNITED STATES PATENTS Name Date Griep Jan. 10, 1911 Lee June 24, 1930 Oldham Nov. 19, 1935 Grantham Aug. 22, 1939 Taylor Jan. 30, 1940 Saupp Apr. 2, 1940 Lawson Dec. 31, 1940 Schmitt et a1. Dec. 21, 1943 Lee July 11, 1944 FOREIGN PATENTS Country Date Great Britain Mar. 26, 1909 Great Britain Jan. 25, 1934

Images