US3176641A - Electrically controlled sewing machines - Google Patents

Description

A ril 6,1965

Filed Oct. 3. 1962 4 Sheets-Sheet 1 April 6, 1965 G. w. PALMER ELECTRICALLY CONTROLLED SEWING MACHINES 4 sheets-sneak; 2

Filed Oct. 3, 1962 Fparye MI/zamPalmar April 6, 1965 e. w. PALMER 3,176,641

7 ELECTRICALLY CONTROLLED SEWING MACHINES Filed Oct. 5, 1962 4 Sheets-Sheet a m wf e eoryeWEf/zazzzfialmer A ril 6, 1965 G. w. PALMER ELECTRICALLY CONTROLLED SEWING MACHINES 4 Sheets-Sheet 4 Filed Oct. 3, 1962 61 02" a WEI/1am Palmar In. 7

United States Patent 3,176,641 ELECTRHCALLY CONTROLLED SEWlNG MACS George William Palmer, Leyton, London, England, msignor to Lights London Limited Filed Oct. 3, 1962, Ser. No. 228,123

Claims priority, application Great Britain, Oct. 19, 1961,

37,572/61 7 Claims. (Cl. 112219) This invention relates to electrically driven sewing machines. In the operation of such sewing machines it is customary to stop the sewing needle of the machine simply by declutching the drive from the motor to the sewing needle. Upon declutching, the inertia of the moving parts of the needle drive causes the needle to oscillate vertically and come to rest in a position which may be anywhere in the range of movement of the needle. If the machine operator, for example, desires to remove a workpiece from the machine and declutches the drive to the needle for this purpose it may well happen that the needle sops whilst it is in engagement with the workpiece. This in turn means that the needle has to be brought manually into a position outside the workpiece before removal of the workpiece can take place.

According to the present invention, an electrically driven sewing machine comprises an electric motor having a first shaft, driving wheel means freely rotatably mounted on the first shaft, a sewing needle drive including a second shaft, driven wheel means mounted on the second shaft for co-operation by means of an endless band with the driving wheel means, electromagnetic clutch means including a driving member mounted on the first shaft for rotation therewith and a driven member mounted for rotation with the driving wheel means, elec-- tromagnetic brake means including a first element mounted on the second shaft for rotation therewith and a second element for attracting and thereby arresting the first element upon energization of the brake means, cam means provided on the second shaft and adapted during rotation thereof to actuate contact means electrically connected with the brake means and switching means adapted to switch a source of electrical power from the clutch to the brake means thereby to-elfect energization of the brake means upon actuation of the contact means and consequent arresting of the second shaft.

It will be apparent that with a sewing machine according to the invention upon switching of electric power to the brake means energization of the brake means does not take place until the cam means have actuated the contact means. In the interval between de-energization of the clutch and energization of the brake means the needle of 3,176,641 Patented Apr. 6, 1965 FIGURE 4 is a front elevation of an upper part of the machine of FIGURES lto 3, the casing of the machine being partly broken away to illustrate details of the interior thereof; 7

FIGURE shows a detail of the machine; and

FIGURE 6 shows in diagrammatic form an electrical circuit of the machine. 7

Referring to the drawings, an electrically'driven sewing machine, generally designated 1, is provided with an induction motor 2 the shaft 3 of which, otherwise herein called the first shaft, is arranged horizontally below a table 4 of the machine to extend in a direction from front to rear of the table. A head casting 5 of the sewing machine which is mounted on the upper side of the table 4 also extends from front to rear of the table so that a needle drive shaft 6, otherwise referred to herein as the second shaft, in the machine head is disposed parallel with the first or motor shaft. The drive from the second shaft 6 to the needle for vertical reciprocation of the latter is largely of conventional known form and includes a collar 7 in which a vertical post 8 which at its lower end carries a needle 9 is mounted for vertical reciprocation by means of a link 10 and eccentric 11 of known form, the

the sewing machine reciprocates due to the inertia of the FIGURE 1 is a side elevation of an electrically driven sewing machine according to the invention;

FIGURE 2 is a fragmentary side elevation, partly in section of the machine of FIGURE 1 drawn to a larger scale than that figure;

FIGURE 3 is a sectional side elevation drawn to a larger scale than FIGURE 1 of a rear part of the machine;

It follows, therefore, that the needle can be eccentric 11 being keyed to the forward end of the shaft 6. A presser foot 12 is arranged for movement parallel with the direction of movement of the sewing needle 9. To this end the foot 12 is carried on a vertical rod 13 which is slidable in collars 14 and 15. On the rod 13 is secured a member 16 which has a laterally projecting abutment piece 17, the latter co-operating with a cam portion 18 of a lever 19 Which is pivoted at 20 for movement in a vertical plane. It will be seen that on upward and outward rotation of lever 19the cam portion 18 co-operates with the abutment piece 17 to effect lifting of the foot 12.

Above the member 16 there is fixed on the rod 13 a member 21 the function of which is hereinafter described. Between member 21 and collar 15 a helical spring 22 is provided which biasses the rod 13 downwardly. Thus, upon release of lever 19 from its uppermost position, the spring 22 effects downward movement of the presser foot.

A driving wheel 25 (see FIGURE 3) in the form of a pulley is freely rotatably mounted on the first shaft by means of a ball race 26 and co-operates by means of an endless belt 27 with a driven pulley 28 keyed to the second shaft 6 and forming part of a fly wheel 29. On the rear face of the driving wheel remote from the motor is secured as by screws 36 to rotate with the pulley a plate 31 of an electromagnetic clutch 32. The plate 31 is formed with a rearwardly projecting central boss 33 the outer surface of which is formed with splines 34 extending longitudinally of the motor shaft 3. Complementarily engaged on the splines of the boss 33 is a driven plate member 35 of the clutch provided on its rear face with a suitable friction lining. The plate member 35 can thus move axially relative to the wheel 25 but is retatable with that wheel. Opposed and adjacent to the driven plate member 35, the clutch includes a driving plate member 36 which is secured to the first shaft 3 as by screw 37 and which has a suitable friction lining on its forward face. On the side of the driving plate meniber 36 remote from the driven plate member 35 is an energizing clutch coil 38 which is disposed in a housing 39 arranged concentrically with the first shaft 2 and carried on a bracketed secured to the casing of the motor 2.

The housing 39 includes inner and outer cylindrical walls 42 and 43 concentric with shaft 2 and closed at rear ends thereof by radial wall 44 which is secured to a plate 45 in turn secured to bracket 49. At the forward ends of the walls 42 and 43, the periphery of the driving plate 7 the wall 43 whilst a rearwardly projecting annular wall 46 of the member 36 closely overlies the forwardend of inner wall 42. Thus the annular gap between the walls 42 and 43 is substantially closed by driving plate men her 36. On rotation of shaft 2 the member 36 rotates therewith and when coil 38 is energized driven plate member 35 is magnetically attracted to member 36 and moves into contact therewith along the splines 34. In this way the driving wheel 25 is caused to rotate with the motor shaft 3. V 7

On the second shaft 6 near the driven pulley 28 is mounted a brake plate which is keyed to the driven pulley so as to be capable of limited axial movement relative thereto. To this end on the rear face of pulley 28 is secured a boss 51 formed on its outer surface with axially extending splines with which the brake plate 5 co-operates. On the side of the brake plate 5% remote from the driven pulley is provided an annular brake housing 52 disposed concentrically with the second shaft 6 and secured to a plate 53 in turn secured to a bracket 54 carried on the head casting 5. Within the brake housing 52 is provided a brake energizing coil 55 which, when energized, magnetises a front plate 56 of the housing adjacent the brake plate 5% causing the latter to be attracted to the housing and thereby stopping the second shaft. The forward and rear surfaces of the housing front plate 56 and brake plate 50 respectively are suitably friction lined.

On an end of the second shaft 6 projecting rearwardly of bracket 54 is provided a cam 60 which is secured to the shaft for rotation therewith. Engaging the cam and mounted on the rear face ofthe bracket 54 is a cam follower 61 which is pivoted at 62 .andbiassed by spring 63 (see FIGURE 5) towards the cam. The follower carries one contact 64 of a pair of contacts, the other contact 65 of the pair being mounted on an insulated support 66 carried on the rear face of the bracket54. The action of the'cam follower biassing spring is to bias towards closure the pair of contacts whilst urging the follower into contact with the cam and rotation of the cam causes the follower to be-rnoved, once per revolution,

under the action of the biassing spring to efiect closure of a the contacts. As shown in'FIGURE 5 the cam 6tlhas a flat 67 and When the flat is engaged by the follower 1 the contacts 64- and 65 are closed. 7

Referring now to FIGURE 6, a field winding 79 of the induction motor 2 is supplied from an alternating current supply 71 by way of a double pole mains switch 72.

Suitably, the alternating current supply is a 250 volts S0 1 V movement of a contact arm 76 of the microswitch 74 upon raising or lowering of the presser foot 12. When the presserfoot is raised the arm 76 is biassed into engagement with afirst contact 77 of the microswitch and when the presser foot is lowered the element 75 moves the arm 76 into contact with a second contact 78 of the microswitch whereupon the output of the rectifier energizes the clutch coil 38.

Connected between the contact 77 and the output side of the rectifier 73 opposite that to which the contact arm 76 is connected are parallel branches respectively including a lamp 84 mounted on the side of the head of the machine and the brake coil in series with the cam actuated contacts 64 and 65. It will be apparent that when the contact arm 76 engages contact 77 in the raised position of the presser foot, the lamp 8% and coil 55 and contacts 64 and 65 are connected across the rectifier 73 so that when the cam causes contacts 64- and to close, the brake is energized and effects stopping of the needle 9, the cam 6% being appropriately shaped to cause the contacts 64 and 65 to close when the needle is in its uppermost position.

It will be noted that the presser foot does not have to be fully raised to eiiect actuation of the microswitch 74. Because of this, and as hereinafter described, the machine is particularly suited for use with the device described in co-pending application No. 170,622.

For a variety of reasons, for example, stiffening of bearings, excessive wear on parts or inadequate lubrication, it may infrequently happen that upon energization of the brake coil, the needle stops'in some position other than that predetermined by the shape of the cam 60. In this eventuality, it is desirable that the operator of the machine should be able to bring the needle to its uppermost position without having manually to rotate pulley 28. To this end there is connected between contacts 77 and 78 of microswitch 74 a branch circuit comprising a variable resistor 81 in series with contacts 82 and 83 of a microswitch 84 disposed on the side of the machine and adjacent microswitch 74. The contacts 82 .and 83am actuated to close by movement of the element by the lever 19 to a position slightly above that at which the element 75 permits the contact arm of the microswitch 74 to engage contact 77. If the lever 19 is moved so that the element 75 passes the position at which the contacts 82 and 33 close, these contacts immediately re-open. In use the lever 19 is moved so that the element 75 momentarily closes the contacts of microswitch 84 and when this happens the clutch coil 38 is energized in series with resistor 81 and drives the machine until the cam 60 once again closes contacts 64 and 65 to energize the brake coil and bring the machine needle to its uppermost position. The resistor 81 is adjusted so that if the clutch'coil is still energized when contacts 64 and 65 close, the clutch will slip as a result of the load imposed on the needle drive by the brake. It will be noted that the resistor 81 is mounted on the side of the head of the machine.

In operation of the machine, the foot is raised to its uppermost position by lever 19 and the switch 72 is closed- A workpiece is then inserted below the presser foot and the foot is lowered whereupon contact arm 76 closes with contact 78 and the clutch coil 38 is energized to initiate sewing. When it is required to stop sewing the lever 19 is moved to raise the presser foot 12 and at the same time effect closure of contact arm 76 with contact 77. At this instant the clutch is de-energized and the rive to the needlecontinues to move under its own inertia until the cam 60 reaches the position at which it closes contacts 64 and 65 and thereby energizes the brake coil 55 to stop the needle drive with the needle in its uppermost position.

As mentioned above the invention is particularly suitable for use with the device described in co-pending application No. 170,622. When used with this device the presser foot of the machine is provided with a downwardly extending projection which engages with the sewing track of the device.

Initially, the presser foot is lowered on to the top of the device so that the projection on the lower side of the presser foot contacts the top sheet of the device. The clutch winding is not, however, energized until the projection on the presser foot is lowered into the sewing track of the device. 7 When the projection on the presser foot is so lowered, the machine commences sewing. At the end of the track the presser foot is automatically raised on the ramps provided at the end of the track and the raising of the presser foot effects automatic stopping of the machine with the needle in its predetermined position, suitably its uppermost position. If the needle does not stop in its predetermined position, it is brought to this position by movement of lever 19 to effect momentary actuation of microswitch 84. s

I claim: 1. In a sewing machine having a needle mounted for movement up and down along a defined path and an electric motor for driving the needle in such up and down 7 motion:

(A) a driving shaft rotatable with the electric motor;

(B) a driving wheel mounted for rotation relative to the driving shaft;

(C) electromagnetic clutch means operatively associated with the driving shaft and the driving wheel and comprising (1) a coupling element movable between a clutch engaged position at which the coupling element constrains the driving wheel to rotate with the driving shaft and a clutch disengaged position at which the coupling element permits the driving wheel to rotate relative to the driving shaft, and

(2) first electromagnet means energizable to hold the coupling element in one of its said positions;

(D) needle actuating means comprising (1) a rotatable driven shaft and (2) means for translating rotation of the driven shaft into up and down motion of the needle;

(E) a driven wheel constrained to rotation with the driven shaft;

(F) means providing a rotation transmitting connection between the driving wheel and the driven wheel through which the motor can drive the needle in up and down motion when the coupling element of the electromagnetic clutch means is in its first designated position;

(G) electromagnetic brake means operatively associated with the driven wheel and comprising (1) a brake element movable between a brake disengaged position and a braking position, at the latter of which said brake element is engaged with the driven wheel and with a fixed part on the sewing machine to restrain the driven wheel against rotation, and

(2) second electromagnet means energizable to move said brake element from one to the othe of its said positions;

(H) means for controlling energization of said first and second electromagnet means from a current source to effect movement of the brake element to its braking position concomitantly with movement of the coupling element to its clutch disengaged position, and for effecting movement of the coupling element to its clutch engaging position concomitantly with movement of the brake element to its brake disengaged position, said last named means comprising (1) switch means,

(2) conductor means connected with said switch means and with the first and second electromagnet means and connectable with a current source, and

(3) manually operable actuator means for said switch means; and t (I) cam means constrained to rotation with the driven wheel and operatively associated with the electromagnetic brake means for causing the brake element to engage the driven wheel when the latter is in a predetermined position of rotation corresponding to a desired position of the needle along its path of motion.

2. The sewing machine of claim 1, further characterized by the fact that said manually operable actuator means for the switch means also serves as an actuator for a presser foot that is movable downwardly to and upwardly from an operative position.

3. The sewing machine of claim 1 wherein the coupling element is movable to its clutch engaged position in consequence of energization of the first electromagnet means and the brake element is movable to its braking position in consequence of energization of the second electromagnet means, further characterized by the fact that: said switch means comprises a double-throw switch having a movable contactor connectable with a current source, and having a pair of terminals that are alternatively connectable with said contactor, depending upon the position of the latter, and which are respectively connected with the first and second electromagnet means, so that said switch efiects energization of one of said electromagnet means concomitantly with de-energ'ization of the other.

4. The sewing machine of claim 3, further characterized by the following:

(A) said switch means also comprises a single-pole single-throw switch connected between the second electromagnet means and that terminal of the doublethrow switch with which the second electromagnet means is connected, so that the second electromagnet means cannot be energized unless the single-throw switch is closed; and

(B) the cam means comprises an actuator for said single-pole single-throw switch whereby the latter is closed only when the driven wheel is in its said predetermined rotational position.

5. The sewing machine of claim 1 wherein the coupling element is movable to its clutch engaged position in consequence of energization of the first electromagnet means and the brake element is movable to its braking position in consequence of energization of the second electromagnet means, further characterized by the following:

(A) said switch means comprises a double-throw switch having a movable contactor connectable with a current source and having a pair of terminals that are alternatively engageable by said contactor, depending upon the position of the latter,

(1) one of said terminals being connected with the first electromagnet means, and

(2) the other of said terminals being connected with the second electromagnet means;

(B) another switch is connected in series between the second mentioned terminal of the double-throw switch and the first electromagnet means, said other switch being normally open and being manually actuatable to its closed position to cause the coupling element to move to its clutch engaged position in the event the driven Wheel stops in a position other than said predetermined position of rotation; and

(C) impedance means connected in series circuit with said other switch and the first electromagnet means so that the first electromagnet means exerts a less than normal clutching force with said other switch closed, permitting continued rotation of the driving wheel after the driven wheel is restrained by the braking element.

6. The sewing machine of claim 5, further characterized by the fact that: said impedance means comprises a variable resistor connected between the second mentioned terminal of the double-throw switch and said other switch.

7. The sewing machine of claim 5, further characterized by (A) a presserfoot movable up and down between a lowered operative position and a raised inoperative position;

(B) a manual actuator for the presser foot connected 7 V with the latter and movable in opposite directions to predetermined positions, motion of said actuator in one direction to one of its positions etfecting lowering of the presser'foot to its operative position, motion of the actuator in its opposite direction to another of its positions effecting raising of the presser foot to its inoperative position, and said actuator being. movable further in its said other direction to a special braking position; 7

8 (D) means mechanically connecting the manual actu- References Cited by the Examiner ator with the double-throw switch means whereby 1 UNITED STATES PATENTS movement of the actuator-to its first mentioned position engages the contactor of the double- throw switch 2, 7 10/ 54 Bliedung et a1. 112219 with the first mentioned terminal and movement of 5 2,876,407 3/59 Winz 112-219 the actuator to its second mentioned position engages 2,942,564 6/60 Larys et a1 112-219 the actuator with said other terminal; and 2,962,992 12/60 Johnson et a1. 112-219 (E) means mechanically connecting said actuator with said other switch means whereby the latter is JORDAN FRANKLIN, Primary Examiner.

closed in'consequence of movement of the actuator 10 to its Special braking Position DAVID J. WILLIAMOWSKY, Exammer.

Claims (1)

1. IN A SEWING MACHINE HAVING A NEEDLE MOUNTED FOR MOVEMENT UP AND DOWN ALONG A DEFINED PATH AND AN ELECTRIC MOTOR FOR DRIVING THE NEEDLE IN SUCH UP AND DOWN MOTION: (A) A DRIVING SHAFT ROTATABLE WITH THE ELECTRIC MOTOR; (B) A DRIVING WHEEL MOUNTED FOR ROTATION RELATIVE TO THE DRIVING SHAFT; (C) ELECTROMAGNETIC CLUTCH MEANS OPERATIVELY ASSOCIATED WITH THE DRIVING SHAFT AND THE DRIVING WHEEL AND COMPRISING (1) A COUPLING ELEMENT MOVABLE BETWEEN A CLUTCH ENGAGED POSITION AT WHICH THE COUPLING ELEMENT CONSTRAINS THE DRIVING WHEEL TO ROTATE WITH THE DRIVING SHAFT AND A CLUTCH DISENGAGED POSITION AT WHICH THE COUPLING ELEMENT PERMITS THE DRIVING WHEEL TO ROTATE RELATIVE TO THE DRIVING SHAFT, AND (2) FIRST ELECTROMAGNET MEANS ENERGIZABLE TO HOLD THE COUPLING ELEMENT IN ONE OF ITS SAID POSITIONS; (D) NEEDLE ACTUATING MEANS COMPRISNG (1) A ROTATABLE DRIVEN SHAFT AND (2) MEANS FOR TRANSLATING ROTATION OF THE DRIVEN SHAFT INTO UP AND DOWN MOTION OF THE NEEDLE; (E) A DRIVEN WHEEL CONSTRAINED TO ROTATION WITH THE DRIVEN SHAFT; (F) MEANS PROVIDING A ROTATION TRANSMITTING CONNECTION BETWEEN THE DRIVING WHEEL AND THE DRIVEN WHEEL THROUGH WHICH THE MOTOR CAN DRIVE THE NEEDLE IN UP AND DOWN MOTION WHEN THE COUPLING ELEMENT OF THE ELECTROMAGNETIC CLUTCH MEANS IS IN ITS FIRST DESIGNATED POSITION; (G) ELECTROMAGNETIC BRAKE MEANS OPERATIVELY ASSOCIATED WITH THE DRIVEN WHEEL AND COMPRISING (1) A BRAKE ELEMENT MOVABLE BETWEEN A BRAKE DISENGAGED POSITION AND A BRAKING POSITION, AT THE LATTER OF WHICH SAID BRAKE ELEMENT IS ENGAGED WITH THE DRIVEN WHEEL AND WITH A FIXED PART ON THE SEWING MACHINE TO RESTRAIN THE DRIVEN WHEEL AGAINST ROTATION, AND (2) SECOND ELECTROMAGNET MEANS ENERGIZABLE TO MOVE SAID BRAKE ELEMENT FROM ONE TO THE OTHER OF ITS SAID POSITIONS; (H) MEANS FOR CONTROLLING ENERGIZATION OF SAID FIRST AND SECOND ELETROMAGNET MEANS FROM A CURRENT SOURCE TO EFFECT MOVEMENT OF THE BRAKE ELEMENT TO ITS BRAKING POSITION CONCOMITANTLY WITH MOVEMENT OF THE COUPLING ELEMENT TO ITS CLUTCH DISENGAGED POSITION, AND FOR EFFECTING MOVEMENT OF THE COUPLING ELEMENT TO ITS CLUTCH ENGAGING POSITION CONCOMITANTLY WITH MOVEMENT OF THE BRAKE ELEMENT TO ITS BRAKE DISENGAGED POSITION, SAID LAST NAMED MEANS COMPRISING (1) SWITCH MEANS, (2) CONDUCTOR MEANS CONNECTED WITH SAID SWITCH MEANS AND WITH THE FIRST AND SECOND ELECTROMAGNET MEANS AND CONNECTABLE WITH A CURRENT SOURCE, AND (3) MANUALLY OPERABLE ACTUATOR MEANS FOR SAID SWITCH MEANS; AND (1) CAM MEANS CONSTRAINED TO ROTATION WITH THE DRIVEN WHEEL AND OPERATIVELY ASSOCIATED WITH THE ELECTROMAGNETIC BRAKE MEANS FOR CAUSING THE BRAKE ELEMENT TO ENGAGE THE DRIVEN WHEEL WHEN THE LATTER IS IN A PREDETERMINED POSITION OF ROTATION CORRESPONDING TO A DESIRED POSITION OF THE NEEDLE ALONG ITS PATH OF MOTION.

Images