US2971484A - Dial speed mechanism for a sewing machine - Google Patents

Description

Feb. 14, 1961 s. J. HAMLETT 2,971,484

DIAL SPEED MECEANISM FOR A SEWING MACHINE Filed Jan. 2s, 1959 United States Patent O DIAL SPEED MECHANISM FOR A SEWING MACHINE Sidney J. Hamlett, Parma, Ohio, assignor to White Sewing Machine Corporation, Lakewood, Ohio, a corporation of Delaware Filed Jan. 28, 1959, Ser. No. 789,667 3 Claims. (Cl. 112--220) The invention relates to an adjustable speed regulator for an electric drive motor ina sewing machine.

One of the principal objects of the invention is to provide a speed regulator in combination with a sewing machine that is directly responsive to the output speed of the sewing machine and not directly responsive to the output torque.

Another object of the invention is to provide a centrifugally operated speed governor in combination with a sewing machine having an electric drive motor operating at substantially full torque under variable driving conditions.

Yet another object of the invention is to provide a sewing machine speed governor as set forth in the preceding object, that can 4be controlled or regulated from a remotely located control device such as a dial.

Still another object of the invention is the provision of a speed governor for the drive of a sewing machine, the drive preferably being an electric motor, which governor can be so regulated by a portion of an operators body through a control lever, that the speed of the drive can be closely controlled up to a selected maximum speed setting of the governor. The control lever permits a sewing machine operatorto accelerate and decelerate the machine speed at a desired rate and/or stop the machine preferably While the operator has two hands free to handle the article -being sewed. Accordingly, it is desirable that the control lever be operated with a portion of the operators body other than the hands, such as a knee, foot, etc., so as to leave the hands free.

The invention further resides in certain novel features of construction, combinations and arrangements of parts and further objects and advantages of the invention will be apparent from the following description of the preferred embodiment thereof, described with reference to the accompanying drawings forming a part of this specification and wherein the same reference characters represent corresponding parts throughout the several views,- and in which:

Fig. l shows a fragmentary elevational view of a sewing machine standard embodying a preferred form of the invention and with part of the housing removed to better show the invention;

Fig. 2 is a vertical sectional view along line 2-2 in Fig. l;

Fig. 3 is a horizontal sectional view along line 3-3 in Fig. 2;

Fig. 4 is a fragmentary plan view of a centrifugally operated speed governor for the sewing machine drive motor;

Fig. 5 is a side elevational view of the governor; and

Fig. 6 is the other side elevational view of the governor showing concentric commutator rings and the brushes therefor.

It is to be understood that the invention is not limited to the details of construction and arrangements of parts shown in the drawing and hereinafter described in detail, but is capable of being otherwise embodied and of Patented Feb. 14, 1961 being practiced or carried out in various ways. It is to be further understood that the phraseology or terminology employed herein is for the purpose of description and there is no intention to herein limit the invention beyond the requirements of the prior art.

Referring to Fig. l, the sewing machine is comprised of a main drive shaft 10 mounted in a standard 11 and driven by an electric motor 12, and also includes a pair of geared together shafts 13 and 14 driven by the main drive shaft 10 by means of a pulley belt arrangement 15. The main drive shaft 10 drives the usual mechanism in the upper part of the sewing machine and is carried in the gooseneck of the machine. The shafts 13, 14 drive the usual associated mechanism mounted in the base, or the lower part of the machine, as is well understood in the art. v

A centrifugally operated governor 16, fixed to the end of shaft 14 for controlling the effective driving speed of the motor 12, can be regulated by manually setting a dial indicator 17 to any desired sewing speed up to the maximum speed capacity of the machine. The dial indicator 17 controls the relative position of a pivotally suspended, dielectric wedge 18 through a sliding linkage mechanism 20. However, the selective positioning of the wedge 18 is not effective tostart the motor 12 or to regulate the sewing speed of the machine through the governor 16 until the operator moves a control lever mechanism 21 to the right, Fig. l, and presses the wedge 18 to the left. This causes a positively controlled, variable position, electrical contact 23, Fig. 5, to be moved into contact with a freely suspended, complementary contact 24 which is susceptible to outward movement under the action of centrifugal forces arising during the rotation of the shaft 14.

Not only is the Contact 23 brought into Contact with the other contact 24 for starting the motor, but the contact`23 is continued to be moved against the other contact 24 until it has reached its predetermined position as governed by the setting of the dial indicator 17 and the resulting positioning of the wedge 18. Should the shaft 14 have an excessive rotative speed, the other contact 24 will y outwardly away from the positively controlled contact 23, and the supply of electrical energy to the motor 12 will be momentarily shut off, caused by the breaking of the contacts 23, 24. When the shaft 14 slows down due to the load thereon, the contact 24 again closes with the contact 23 and energy is again supplied to the motor 12. The opening and closing of the contacts 23, 24 occur at such rapid intervals that the starting and stopping of the motor 12 is imperceptible to the operator. But, the result is that the sewing machine is driven at speeds not exceeding the preselected desired speed.

More particularly, the shaft 10 is journalled in the upper part of the sewing machine standard 11 and extends through the usual sewing machine gooseneek, not shown. The motor 12 is pivotally supported in the standard 12 by means of a pair of trunnions 25 in a motor support bracket 26 as shown and described in applicants copending U.S. patent application, Serial No. 758,455, tiled September 2, 1958. A coil spring, not shown, continuously biases the motor 12 in a clockwise direction, Fig. l, about its trunnions 25 so that its rubber drive roller 27 frictionally engages and drives a drive wheel 28 fixed onto the shaft 10, the outer end of the shaft 10 being provided with a handwheel 30.

The pulley belt arrangement 15, which drives the shaft 13 from the shaft 10, is comprised of a pulley wheel 31 on the shaft 10 and a pulley wheel 32 on the shaft 13 with a pulley V-belt 33 in driving connection with the pulley wheels 31, 32.

As pointed out, the shafts 13, 14 are geared together with two meshing gear wheels 34, respectively, for forming a driving connection between the two shafts 1.3, 14, the gear wheels 34, 35 preferably doubling the rotative speed of the shaft 14 relative to the shaft 13. It will be noted that the governor 16 is Xed to the en'd of the high speed shaft 14 so as to give a greater speed sensitivity and more closely control the speed of the sewing machine. More specifically, since it is preferable that the speed of shaft 14 be twice as great as that of shaft 13, the centrifugal force acting upon the speed sensitive contact 24 will be multiplied four times over that of the shaft 13 so any change of speed wiil be four times greater on shaft 14 than on shaft 13 and accordingly the sensitivity of the governor 16 is multiplied.

Each of the contacts 23, 24 are connected into one of the electrical supply lead lines of a motor control circuit, not shown. The supply lead lines are comprised of a pair of electrical conductor wires 36, 37, respectively leading to the motor 12 from a pair of support blocks 38, 39. The blocks 33, 39 are connected to the side of a journal block itl in which one end of each of the shafts 13, 14 is journaled. The electrical wires 36, 37 terminate in a pair of electrically conductive, resilient contact strips or elements 36', 37', Figs. 3, 4, 6, respectively, having small, bu'tton- like brushes 36, 37 on the free ends thereof which bear against two coaxial, electrically conductive commutator rings 42, 43 secured to a flat Side Wall of the disk-like dielectric body 44 of the governor 16, Fig. 6.

The contact 24 is comprised of an electrically conductive, resilient, metal strip with a contact point or button on its free end and is rigidly supported at its otherend by means of an electrically conductive angle bracket 47 riveted to the body 44 of the governor 16 on the side opposite to the commutator rings 42, 43. The contact Z4 is electrically connected to the outer commutator ring 43 by means of electrically conductive rivets, such as copper rivets.

The contact 23 is disposed in side-by-side chordal relationship with the contact 24 and is similarly constructed and fastened at its one end to the governor body 44 by means of an electrically conductive angle bracket 50 riveted thereto. The contact 23 is electrically connected to the inner commutator ring 42 by means of electrically conductive rivets, such as copper rivets.

As stated, the contact 24 has one end free toswing outwardly in a radial direction away from the contact 23 under the action of centrifugal force. However. the corresponding end of the contact 23 is controlled by a governor actuating mechanism 51, the latter being engaged by the wedge 18 upon the actuation ofthe linkage mechanism 21 to the right. Fig. 1, by the operator. It is to be understood that although the lever control mechanism 21 is shown comprised of a horizontally extending arm 52 pivotally connected to and operating an L-shaped dog 53, pivotally supported upon the base portion of the standard 11 and with its free end adapted to `engage the wedge 18, the lever control mechanism 21 can take on any of many shapes and forms and can be operated with a part of an operators body such as a hand, foot, knee, etc., and/or by other known means, it being preferable that the lever 52 not be actuated with ones hands in the instant preferred embodiment so that the hands will remain free for handling the sewing article. The governor actuating mechanism is comprised of a specially-shaped rocker arm 55 pivotally supported along one edge by means of a pintle 56 mounted in a generally U-shaped support bracket 57 riveted to the governor body 44. The pivoted end 55a of the rocker arm 55 is connected to an end of a push-pull wire link 58 which has its other end fixed to the contact 23 near the outer end thereof so as to provide a greater sensitivity of adjustment. The other or free end of the rocker arm is provided with a button 5511.

The button SSb is acted upon by a button on one end of a relatively long rocking arm et) pivotally .supported intermediate its ends on a support ange 39a of the support block 39 by means of a pivot pin 61. A coil spring 62 acts against the rocking arm 60 to bias the same in a counterclockwise direction about its pivot pin 61, Fig. 3, so that the rocker arm 55 is continuously engaged by the rocking arm d@ and urged in a'clockwise direction about the pintle 56. The clockwise movement of the rocker arm S causes the contact 23 to be moved inwardly away from the freely movable contact 24 in a motor stopping direction.

The spring-biased rocking arm 6i) is adapted to be engaged by the pivoted wedge 18 under the levering action of the dog 53 of the lever control mechanism 21.

The wedge 1S is generally -in the shape of a right triangle with its sloping hypotenuse side being engaged by the dog 53.

The lower end of the sliding linkage mechanism 2i) has the Wedge 13 pivotally suspended therefrom. The sliding linkage mechanism 2t? is comprised of a vertical ram 64 slidably connected to and guided on'two vertically spaced guide screws 65 threaded into the wall of housing 11 and extending through two guide slots in the ram 64. The ram 6ft is moved vertically downwardly by turning the dial indicator in a clockwise direction, Fig. l, and upwardly by turning the indicator 17 in a counterclockwise direction. The position of the dial indicator 17 vin Fig. l preferably represents the lowest machine operating speed and not the motor stop position in the instant embodiment.

The dial 17 is connected to the ram 64 by means of aY crank arm 66 and a link 67, which is pivotally connected to the free end of the crank arm @56 and to the upper end of the ram 54 by means of a sliding slot, pivotal connection. The crank arm do is xed to the dial 17 so as to turn therewith. Both the dial 17 and the crank arm 66 rotate in a journal 63.

It will be noted that the dial 17 is provided with a pointer 17a having an index mark thereon and that the pointer 17a cooperates with the indicia marks on the outside of the standard 11. The indicia marks in this instance are scaled from sewing speeds of 2 to 12 indication.

From the foregoing it is apparent that as the dial 17 is turned in a clockwise direction, Fig. 1, that the wedge 18 will be further projected between the actuating mechanism 51 and the lever control mechanism 21. Tnistcauses the distance between the two mechanisms 21, 51 to be increased and accordingly permits greater speeds of the sewing machine by moving the controlled contact 23 a greater distance toward the left and into iirmer engagement with contact 24, Fig. 5, so as to require a greater centrifugal force to cause the contact 24 to move away from the contact 23 and break the motor control circuit. The dog 53 of the lever control mechanism 21 is limited in its movement to a predetermined amount -in both directions, about its pivot pin, Fig. l, by the sides lil and 71 of the opening in the bottom wall of the standard or housing 11 through which the dog S3 protrudes.

The preferred form of the invention having been described, it will be understood that the invention can be modified to adapt it to various circumstances and conditions and it is accordingly desired to comprehend within the purview of this invention such modifications as may be considered to fall within the scope of the appended claims.

Having described my invention, I claim:

1. In a sewing machine, a drive motor, an adjustable centrifugal governor including a iirst contact movably responsive to centrifugal forces and va second contact cooperating therewith for controlling energization and deenergizaton of said motor, selectively settable control means operable to adjust said second contact relative to said first contact to establish a preselected speed of said motor, said settable control means being ineffective to close said first and second contacts and additional control means operable by an operator to adjust said second contact relative to said first contact without disturbing the adjustment of said second contact effected by said settable conrol means for energizing and de-energizing said motor and for varying the speed of the motor up to said preselected speed.

2. In a sewing machine, a drive motor, a centrifugal governor including a first contact movably responsive to centrifugal forces and a second contact cooperating therewith for controlling energization and de-energization of the motor, selectively settable control means including a part movable in one direction to adjust said second contact relative to said first contact to establish a preselected speed of said motor, said settable means being ineffective to close said first and second contacts, and means including a control element movable under the control of an operator to displace said part in another direction different from said one direction to adjust said second contact relative to the first contact without disturbing the adjustment of said second contact effected by said part for energizing and de-energizing the motor and for varying the speed of the motor up to said preselected speed.

3. In a sewing machine, an electric drive motor, a centrifugal governor including a first contact movably responsive to centrifugal forces and a second contact cooperating therewith for controlling the energization and deenergization of said motor, mechanism including a pivotal rocker arm for adjustably varying the operative position of said second contact, a spring acting on said rocker arm to move the latter in one direction for normally separating said contacts, means under the control of an operator for moving said rocker arm against the spring load including a movable actuating member, a wedge element mounted for pivotal movement about a horizontal axis and interposed between said actuating member and said rocker arm to operatively connect said actuating member and said rocker arm, and selectively settable means for moving said wedge element in a vertical direction to move said rocker arm against said spring to selectively vary the position of said second contact for establishing a selected speed of said motor, said settable means being ineffective to cause engagement of said first and second contacts, said actuating member when moved by an operator being effective to pivot said wedge element about the horizontal axis to energize and deenergize said motor and to vary the speed of the motor up to said preselected speed.

References Cited in the file of this patent UNITED STATES PATENTS 2,337,066 Schmitt et a1 Dec. 2l, 1943 2,477,150 Snyder et al July 26, 1949 2,588,301 Snyder Mar. 4, 1952 2,850,996 Howard Sept. 9, 1958 FOREIGN PATENTS 623,688 Germany Ian. 2, 1936

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