JPH0630148Y2 - Sewing machine foot presser lifting device - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a cloth presser foot for a sewing machine, which elevates and lowers the cloth presser foot by an electromagnetic force in order to carry in and carry out cloth to and from the sewing machine sewing section and to change the sewing direction. Lifting equipment.

[Prior Art] Conventionally, as a lifting and lowering device for this kind of work clamp,
Those described in Japanese Patent Laid-Open No. 192767 and Japanese Utility Model Laid-Open No. 52-157949 are known.

[Problems to be Solved by the Invention] However, in the above-described conventional presser foot lifting device, when the presser foot is lowered all at once by the electromagnetic force of the drive source, the presser foot violently collides with the needle plate, which causes an uncomfortable feeling. There was a drawback that noise was generated.

Also, in the Japanese Utility Model Laid-Open No. 52-157949, the voltage applied to the solenoid as the drive source can be controlled by a variable resistor to adjust the lifting speed of the work clamp foot. If it is controlled to eliminate the unpleasant impact sound, there is a drawback that the lifting speed of the work clamp foot becomes slow and the work efficiency is lowered.

[Means for Solving Problems] The present invention is directed to an outer frame 15a in which a shaft portion of a plunger is loosely fitted in a moving space of a plunger 16 of a linear reciprocating electromagnetic drive device that raises and lowers a presser foot. A partition body (39) is provided which communicates with the atmosphere through a slight gap with the bearing part of the, and keeps the space for moving the plunger inside the outer frame airtight so as to divide the plunger into one and the other in the moving direction of the plunger. The partition body is provided at a position where the volume of the space A on the moving direction side of the plunger in the direction of lowering the work clamp foot is at least smaller than the volume of the space B on the other side, thereby eliminating the conventional drawbacks. The purpose is to

[Embodiment] FIG. 1 is a rear view of a sewing machine equipped with the work clamp foot lifting device of the present invention. In the figure, 14 is a working hole 13 opened for assembling and adjusting the internal operating mechanism.
It is a well-known window plate that closes the window. A shaft reciprocating electromagnetic drive device (push pool solenoid) 15 is fixed to the outside of the window plate 14, and a plunger 16 is attached to the window plate 14.
It is arranged to operate parallel to the surface of the. The rotary shaft 17 is rotatably supported with respect to the window plate 14 so that both ends thereof penetrate the window plate 14 and project inward and outward. The other end of the arm 18 having one end connected to the plunger 16 is fixed to the outer end of the rotary shaft 17, and the inner end of the rotary shaft 17 has one end axially connected to one end of the horizontal link 19. The other end of the arm 20 is fixed.

Reference numeral 21 denotes an L-shaped link rotatably supported by a shaft 22 inside the sewing machine arm, which is connected to the other end of the horizontal link 19 via a fixing pin 23 and an elongated hole 24, and is horizontal in FIGS. When the link 19 is moved to the left, the L-shaped link 21 rotates clockwise and the L-shaped link 21
When the is turned clockwise, the movement of the
It is made to not be transmitted to.

Reference numeral 26 denotes an L-shaped actuating arm that is rotatably supported around a central portion inside the sewing machine arm, and one end of which is L-shaped.
It is rotatably connected to the connecting rod 25 connected to the arm 21a of the mold link 21. The interlocking arm 27 is provided at its lower end with a bent portion 27a that is bent inward and erected, and its upper end is the operating arm 2
The other end of 6 is rotatably supported.

Reference numeral 2 is a presser bar which is fixed to the lower end of the presser foot 1 and can be vertically moved up and down. A presser bar hanger 28 fixed to the presser bar 2 and a presser pressure adjusting screw 32 screwed to the machine frame are wound by a spring. 31 is compressed and arranged, and the presser bar 2 is constantly pressed downward.
The bent portion 27a of the interlocking arm 27 extends below the holding bar 28.

The switch for opening and closing the drive circuit of the electromagnetic drive device 15 is provided, for example, at the foot plate for driving the sewing machine or in the vicinity thereof, or at an appropriate position on the sewing machine arm or the sewing machine table. Furthermore, the lower end of the interlocking rod 37 is linked to a known knee raising lever via a link mechanism, and can be moved up and down by an operator's knee operation.

The electromagnetic drive device 15 is as shown in detail in FIG. 3, and its structure will be described below. A cylindrical electromagnetic coil 38 is fixed to the inner circumference of the outer frame 15a, and a plunger 16 is loosely fitted inside thereof so as to be reciprocally movable in the arrow direction. The partition 39 is fixed to the outer frame 15a, and has a function of dividing the space for moving the plunger 16 into two spaces A and B while keeping airtightness. These spaces A and B communicate with the atmosphere through a slight gap between the shaft of the plunger 16 and the bearing of the outer frame 15a in which it is loosely fitted. In addition, the partition 3 is made smaller so that the volume of the space A is smaller than the volume of the space B.
Position 9 is set. The cushioning rubber 40 is fixed to one side of the plunger 16 in the moving direction, and the other end has a truncated cone shape (convex portion) that matches the recessed portion of the outer frame 15a.

[Operation of the Invention] This invention has the above-mentioned configuration, and its operation will be described below.

When the electromagnetic coil 38 of the electromagnetic drive device 15 is excited by an appropriate switch, the plunger 16 moves to the left, and when the electromagnetic coil 38 is demagnetized, the plunger 16 moves.
Moves to the right (the direction in which the convex portion and the concave portion separate) due to the elastic force of the coil spring 31.

When the plunger 16 moves to the left, the arm 18,
Since 20 rotates counterclockwise about the rotating shaft 17, the L-shaped link 21 swings clockwise through the link 19 and the operating arm 26 rotates counterclockwise through the connecting rod 25. Move. As a result, the interlocking arm 27 is pulled up and the presser bar hanger 28 is lifted against the coil spring 31, so that the presser bar 2 or the presser foot 1 is raised.

Further, when the plunger 16 moves to the right, each member operates in the opposite manner to the above, and the work clamp foot 1 descends to hold the sewing cloth.

By the way, when the electromagnetic coil 38 is demagnetized, the electromagnetic drive device 15 uses the elastic force of the coil spring 31 to cause the plunger 1 to move.
6 moves to the right all at once as shown by the solid line in FIG. 3, but when observed microscopically, the air in the space A partitioned by the partition 39 is gradually compressed as the plunger 16 moves to the right. As a result, the plunger 16 continues to move at a high speed that is almost the same as the initial speed for most of its stroke, but the speed decreases rapidly near the end of the stroke, and the plunger 16 collides with the inner wall of the outer frame 15a. Then, when it stops, the impact is sufficiently absorbed by the rubber 40.

When the electromagnetic coil 38 is excited and the plunger 16 moves to the left, the air in the space B is compressed by the same principle as above, but the volume of the space B is larger than the volume of the space A. Not as significant as above. However, when the work clamp foot 1 rises, it moves against the winding spring 31, and the more the work clamp foot 1 rises, the more the compression spring 31 is compressed. The jar 16 moves fast at first, but is gradually decelerated, and even in this case, there is almost no impact when the plunger is stopped.

[Advantages of the Invention] The invention of the present application is slightly different from the bearing portion of the outer frame 15a in which the shaft portion of the plunger is loosely fitted in the moving space of the plunger 16 of the linear reciprocating electromagnetic drive device for raising and lowering the work clamp foot. A partition body (39) is provided which divides the space for moving the plunger inside the outer frame into one and the other in the moving direction of the plunger while keeping the space for moving the plunger inside the outer frame. At least the volume of the space A on the side of the moving direction of the plunger in the direction of lowering the work clamp foot is smaller than the volume of the space B on the other side, and the moving speed of the plunger The compressed air pressure causes the plunger to suddenly decelerate from the vicinity of the end of the travel stroke, so when the foot is lowered, it remains the same as the initial speed up to the end of the travel. It moves at a high speed, but the speed decreases rapidly near the end. Therefore, it is possible to significantly reduce the impact when the work clamp foot touches the upper surface of the needle plate without changing the time required for raising and lowering the work clamp foot, and to raise and lower the work clamp foot that is frequently performed during sewing. There is an effect that it is possible to reduce unpleasant noise associated with, improve the workability of the sewing machine and improve the work environment without lowering the work efficiency.

[Brief description of drawings]

FIG. 1 is a rear view of a sewing machine according to the present invention, FIG. 2 is a perspective view of a main part of the present invention, and FIG. 3 is a sectional view of an electromagnetic drive device. In addition, 1 is a presser foot, 2 is a presser bar, 15 is an electromagnetic drive device, 15a is an outer frame, 16 is a plunger, 38 is an electromagnetic coil, 39 is a partition body, 40 is rubber for cushioning, A and B
Is a space for moving the plunger.

Claims (1)

[Scope of utility model registration request] 1. A cloth presser foot lifting device of a sewing machine, wherein a cloth presser foot that always receives a downward elastic force can be moved up and down by a driving force of a driving device, wherein the driving device has a cylindrical outer frame (1).
5a), a plunger (16) that can reciprocate in the outer frame in cooperation with the presser foot, an air circulation hole that is provided in the outer side wall of the plunger moving direction and connects to the atmosphere, and a driving force is applied to the plunger. A linear reciprocating electromagnetic drive device including an electromagnetic coil (38) for giving a partition body for keeping a space for moving the plunger inside the outer frame airtight and dividing the plunger into one and the other moving direction. (39) is provided at a position where the volume of the space A on the moving direction side of the plunger in the direction of lowering the work clamp foot is at least smaller than the volume of the space B on the other side. Lifting device for work clamp foot.