THREAD CONTROL DEVICE EMPLOYING A THREAD BRUSH, FOR A SEWING MACHINE

Abstract

A sewing machine having a reciprocatory needle and a reciprocatory thread-take-up device to deliver thread to the needle employs a thread control device located between the thread take-up device and the needle to engage and apply light tension to the thread. The thread control device can have an opposed plate and spring wire between which the thread runs and which cooperate to apply spring pressure to the thread. Downstream thereof a thread brush can be employed through which the thread runs. The thread can be further lightly tensioned and laterally positioned by the thread brush. The guide plate or other device can include catcher structure to catch thread escaping the take-up device. The thread control device can help control premature descent of the thread and improperly tensioned stitches.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

Some embodiments of the invention, and of making and using the invention, as well as the best mode contemplated of carrying out the invention, are described in detail below, by way of example, with reference to the accompanying drawings, in which like reference characters designate like elements throughout the several views, and in which:

FIG. 1 is a front perspective view of a head end portion of a domestic sewing machine, with covers removed, showing portions of a thread-control device according to one embodiment of the invention;

FIG. 2 is lefthand perspective view of the head-end sewing machine portion shown in FIG. 1, with a further cover below the needle removed, showing the thread-control device illustrated in FIG. 1 from a different perspective;

FIG. 3 is a view similar to FIG. 2 of the upper portion of the thread-control device there shown with the thread in a first position during descent of the needle;

FIG. 4 is a view similar to FIG. 3 showing the thread in a second position during descent of the needle; and

FIG. 5 is a view in the direction of the line 5-5 of FIG. 2 showing the thread-control device from a different angle along, a wire guide for the thread and the thread held in a take-up lever.

Claims

1. A sewing machine comprising: a) a needle mounted for reciprocal movement toward and away from a workpiece;b) a reciprocating thread take-up device to control the supply of a thread to the needle and workpiece; andc) a thread control device comprising a thread brush located between the thread take-up device and the needle to engage, position and apply tension to the thread as the thread moves between the take-up device and the needle.

2. A sewing machine according to claim 1 wherein the thread control device comprises a guide plate having a thread-engagement surface extending in the direction of travel of the thread between the take-up device and the needle and wherein the thread can run across the thread-engagement surface during operation of the sewing machine.

3. A sewing machine according to claim 1 wherein the thread control device comprises an opposed plate and spring wire cooperable to apply spring pressure to the thread wherein the thread runs between the opposed plates during operation of the sewing machine.

4. A sewing machine according to claim 3 wherein the opposed plate comprise a guide plate, a spring wire and the brush and wherein the guide plate, the spring wire and the brush engage and control the thread flux before the needle penetration and the timing for thread take-up come in the down position.

5. A sewing machine according to claim 3 wherein the thread moves approximately in a straight line as it travels through the thread control device.

6. A sewing machine according to claim 4 wherein the spring wire and the brush applies a light restraining force to the thread.

7. A sewing machine according to claim 4 wherein the spring wire and the brush applies to the thread a restraining force sufficient to control feed of surplus thread to the needle and light enough to permit unimpeded retraction of the thread with the retreating needle.

8. A sewing machine according to claim 4 wherein the spring plate is formed of spring steel wire having a diameter of from about 0.2 mm to about 0.4 mm.

9. A sewing machine according to claim 4 wherein the guide plate has an external profile shaped to support the thread during descent of the take up lever.

10. A sewing machine according to claim 4 wherein the guide plate can catch thread escaping the thread take-up device during downward travel of the thread take-up device.

11. A sewing machine according to claim 10 wherein the guide plate has thread catcher structure comprising a slot beneath the spring wire defined by an upwardly and forwardly projecting shoulder.

12. A sewing machine according to claim 10 comprising a wire guide positioned to facilitate the thread catching action.

13. A sewing machine according to claim 4 being a two-thread lockstitch sewing machine wherein a second thread is supplied to the needle from a reciprocating bobbin beneath a work bed across which a fabric is moved as it is sewn.

14. A sewing machine according to claim 13 being intended for domestic use and oriented in use for the needle to move in an approximately vertical direction.

15. A sewing machine according to claim 13 comprising a thread tensioner located upstream of the take-up device.

16. A sewing machine according to claim 15 wherein the thread tensioner comprises a pair of relatively movable tensioning discs.

17. A sewing machine according to claim 1 wherein the thread demand is controlled by stitch formation and optionally not by the thread take-up device or a return spring for the thread take-up device.

18. A sewing machine according to claim 1 wherein the thread control device controls the thread tension before needle penetration of the fabric and controls the timing of the thread take-up device in the down position.