GB2197350A

GB2197350A - Sewing machine stitch regulator

Info

Publication number: GB2197350A
Application number: GB08726507A
Authority: GB
Inventors: Tsukasa Ando
Original assignee: Aisin Seiki Co Ltd
Current assignee: Aisin Corp
Priority date: 1986-11-14
Filing date: 1987-11-12
Publication date: 1988-05-18
Anticipated expiration: 2007-11-12
Also published as: JPH0351199B2; JPS63125286A; GB8726507D0; GB2197350B

Abstract

A lever 13 is rotatably mountable on a frame 11 of a sewing machine. A feed regulator 17 is connected to the lever 13 for controlling the stitch length in dependence on the amount of rotation of the lever 13. An arm 28 is rotatably mounted on the frame 11. A stepping motor 32 rotates the arm 28 to define a set clearance between the arm 28 and the lever 13 after starting the machine, and to an angle corresponding to the variation of stitch length during operation. Thus the timing of the operation of the feed regulator 17 is constant regardless of variation of stitch length. In operation movement of arm 30 causes movement of arm 28. This causes direct movement of lever 13, or if the arm 28 is moved away from the lever, spring 26 moves the lever via rod 15. Movement of rod 15 causes adjustment of feed regulator 17. Normal feed is conveyed from eccentric 22 via rod 20 to a link 18, a member 50 and then a feed dog (not shown). <IMAGE>

Description

SPECIFICATION Sewing machine stitch regulator Description The invention relates to a sewing machine stitch regulator for controlling stitch length.

The invention provides a regulator comprising a lever rotatably mountable on a frame of a sewing machine, a feed regulator operatively connected to the lever for controlling the stitch length in dependence on the amount of rotation of the lever, an arm rotatably mounted on the frame, and driving means for rotating the arm to define a set clearance between the arm and lever after the starting of the machine and rotating the arm to an angle corresponding to the variation of the stitch length during the operation of the machine.

Thus the timing for the operation of the feed regulator is made constant regardless of variation (increment or decrement) of the stitch length.

DRA WINGS Figure 1 is a side view of a sewing machine stitch length regulator according to the invention; Figure 2 is a view in a direction at right angles to Fig. 1; and Figure 3 is another view in a direction at right angles to Fig. 1; and Figures 4 to Figure 7 are views showing operation of the regulator of Fig. 1.

Referring to Figs. 1 to 3, a sewing machine 10 includes a frame 11 supporting a shaft 12.

A lever 13 is rotatably mounted on the shaft 12, and has a downward extension 13a and a horizontal projection 13b. A pin 14 is mounted on a distal end of the projection 13b. On the pin 14, an upper portion of a rod 15 is rotatably mounted. A lower portion of the rod 15 is provided with a pin 16 on which a right end portion of a link 18 included in a feed regulator 17 is swingably mounted.

On a pin 19 which is mounted on a left end portion of the line member 18, a lower portion of a rod 20 is rotatably mounted. An upper portion of the rod 20, which is generally circular is so mounted on a cam 22 which is eccentrically mounted on a main shaft 21 that the rod 20 may be reciprocably moved in the direction indicated by an arrow A during rotation of the main shaft 21. The resulting reciprocation brings the link 18 into a swinging movement about the pin 16. The link 18 is so operatively connected to a member 50 rotatably mounted on a shaft 23 that the swinging movement of the link 18 causes a swing movement of the member 50 about the shaft 23. The member 50 drives a feed dog (not shown).

A stretched spring 26 is interposed between a hook portion 15a formed at a lower end portion of the rod 15 and a pin 25 fixed to the frame 11 so that the rod 15 and the lever 13 are biased in a counter-clockwise direction. A right side of the downward portion 13a of the lever 13 is in engagement with a pin 29 which is mounted on a distal end of a first arm 28. The first arm 28 is rotatably mounted on a shaft 27 which is fixed to the frame 11. On the shaft 27, a second arm 30 in the form of a sector is fixed. A curved surface of a distal end portion of the second arm 30 is provided with a plurality of equally pitched teeth 31. The teeth 31 are in mesh with a gear 32b fixed on a shaft 32a of a stepping motor 32.Thus, the second arm 30 and the first arm 28 may be rotated in a clockwise or counter-clockwise direction by the shaft 32a with the result that the lever 13 is brought into corresponding rotation. Due to the rotation of the lever 13, the rod 15 and the pin 16 about which the link 18 swings are moved in the vertical direction. The resulting vertical movement varies the stitch length or stroke of the feed dog.

The lever 13 is provided at a left surface with a cam surface 13d, a cam surface 13e and a concave portion 13c therebetween. The concave portion 13c is in engagement with a member 33a of a stitch length setting device 33. The member 33a is so operatively connected to a dial 35 via a screw 34 that, upon rotation of the dial 35, the member 33a is brought into engagement with the cam surface 13d due to counter-clockwise rotation of the lever 13 by the stretching of the spring 26.

On the shaft 32a of the stepping motor 32, an annular plate 36 is fixed. The plate 36 is provided at an outer periphery with a plurality of short slits 36a and a long slit (not shown).

These slits are equally spaced. A sensor 37 can detect the long slit in the plate 36 by a well known optical method. While the sensor 37 is detecting the long slit, the second arm 30 is at its original position shown in Fig. 4.

A sensor 38 can detect all slits in the plate 36, and the amount of rotation may be measured by accumulation at each detection of a slit by the sensor 38. The position of the lever 13 may be detected by a protrusion 39.

The stepping motor 32 acts as a means for driving the second arm 30 and the first arm 28, and is under the control of a micro-computer.

Operation While the machine is not in operation, and the stitch length is set at a maximum in the positive direction, the lever 13 is at a position illustrated in broken line in Fig. 4, and a line between the shaft 12 and the pin 14 makes an angle I relative to the axis of the member 33a. In such conditions the second arm 30 is at its original position, and the pin 29 connected to the first arm 28 (which is movable together with the second arm 30) is at a position P 1. The position P1 is near the down ward portion 13a of the lever 13. A clearance a between the pin 29 and the portion 13a is as small as possible.

Upon rotation of the dial 35 to an angle corresponding to stitch length in one direction prior to operation of the sewing machine, the lever 13 is rotated in the counter-clockwise direction by the stretching of the spring 26 and is transferred to a position illustrated by solid line in Fig. 4. After this transfer, the line beween the shaft 12 and the pin 14 makes an angle 02 relative to the axis of the member 33a. Upon starting of the sewing machine 10 when the lever 13 is in the position illustrated in solid line, a control means (not shown) drives the stepping motor 32 to rotate the shaft 32a through an angle. Thus, the second arm 30 and the first arm 28 movable together therewith are tarnsferred from the broken line position to the solid line position in Fig. 5. As a result of this transfer, the pin 29 on the first arm 28 is moved from the position P1 to a position P2.In such conditions, a clearance J between the pin 29 and the downward portion 13a of the lever 13 should be as small as possible.

When stitch length has to be reduced, a specific signal is fed to the control means.

Then, the control means so drives the stepping motor 32 that the shaft 32a is rotated through an angle. Due to such rotation, the second arm 30 and the first arm 28 are transferred from the broken line position to the solid line position in Fig. 6. Soon after the beginning of the counter-clockwise rotation of the first arm 28, the pin 29 on the first arm 28 is brought into engagement with the lever 13. Then, the lever 13 is also rotated in the clockwise direction and is stopped when the line between the shaft 12 and the pin 14 makes an angle Q, which corresponds to the reduced stitch length, relative to the axis of the member 33a. Upon stopping of the sewing machine 10 at the completion of sewing, the shaft 32a is rotated through an angle by the control means with the result that the second arm 30 is returned to its original position as well as the pin 29 on the first arm 28 from a position P3 to the original position P1.

Claims

1. A sewing machine stitch regulator comprising a lever rotatably mountable on a frame of a sewing machine, a feed regulator operatively connected to the lever for controlling the stitch length in dependence on the amount of rotation of the lever, an arm rotatably mounted to the frame, and driving means for rotating the arm to define a set clearance between the arm and the lever after the starting of the machine and rotating the arm to an angle corresponding to the variation of the stitch length during the operation of the machine.

2. A sewing machine stitch regulator according to Claim 1 wherein the arm includes a first portion engageable with the lever and a second portion movable together with the first portion and drivable by the driving means.

3. A sewing machine stitch regulator according to Claim 1 or Claim 2 wherein the driving means is a stepping motor.

4. A sewing machine stitch regulator as herein described with reference to the drawings.