JPS5937981A - Press rod lift apparatus of sewing machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for raising and lowering a presser bar of a sewing machine using an electromagnetic solenoid.

Conventionally, in this type of device, two types have been proposed: one in which the holding bar is raised by the suction force of a solenoid and lowered by a spring, and the other in which the holding bar is raised by a spring and lowered by a solenoid. However, the former method that uses a solenoid to raise the presser bar has the disadvantage that the presser bar descends rapidly due to the repulsive force of the spring, causing the presser foot to collide with the needle plate or feed teeth, and the latter method that uses the solenoid to lower the presser bar There was a drawback that power consumption was large because the power was continuously applied to the Tsuremade.

The present invention aims to improve these drawbacks, and uses a solenoid to raise the presser bar, but it also does not move when lowering. The purpose is to reduce power consumption by passing a weak current through the solenoid and gently lowering the presser bar while applying play i to the elasticity of the spring.The purpose is to cut off the current to the solenoid except when raising and lowering the presser bar, thereby saving power consumption. shall be.

The present invention will be explained in detail with reference to an embodiment: 1
A presser foot 3 is fixed to the lower end of the presser foot bar which is inserted through and supported by the machine frame 2 of the sewing machine arm.

Reference numeral 4 denotes a support shaft 5 (a horizontal rod that is attached to the shaft, the base end of which is attached to the lifting rod 7 that is sucked by the first solenoid 6, and the tip of which is attached to the protruding rod 1).
are connected to each other via connecting pins 8.9.

A spring 12 is interposed in the locking rod 11 that is attracted by the second solenoid 10, and a retaining step portion 4 is formed at the tip of the horizontal rod 4.
The tip of the locking rod 11 is shown in the locus of &, allowing it to move in and out.

Reference numeral 13 denotes a screw tube screwed into the machine frame 2, into which the presser rod 1 is slidably inserted, and a spring 14 is installed between the screw tube 13 and the presser rod 1 to rotate the screw tube 13 left and right. By doing so, the elasticity of the spring 14 acting on the presser foot 3 is adjusted.

Next, switches Sa and Sb are provided, and relays R1 and R2 are connected to these, respectively, and the six points of the relay R1 are connected to the first solenoid 6, and the *a contacts of relay R2 are connected to the second solenoid 10, respectively.

In addition, there is a limit switch LS near the top dead center of the base end of the stacking rod 4.
is installed, and the a contact of relay R2 is connected to this via self-holding relay R3, and the sliding terminal of variable resistor VR is connected to this. One end of the variable resistor VR is grounded, and the other end is connected to the first solenoid 6 via the relay R30a contact.

When the switch 3a is pressed, the a contact of the relay R1 closes and the first solenoid 6 is energized to attract the lifting rod 7. As a result, the horizontal rod 4 rotates and the presser bar 1 rises against the spring 14, and when the tip of the stacking rod 4 passes over the locking rod 11 and the switch Sa is released, the locking rod 11 is lifted. The engagement stepped portion 4a of the rod 4 is locked, and the presser bar 1 is stopped near the top dead center while being raised.

Next, when switch sb is pressed, the a contact of relay R2 closes,
The second solenoid 10 is energized to cause the locking rod 11 to move back against the spring 12 and disengage from the stacking rod 4.

As a result, the presser bar 1 is lowered by the elasticity of the spring 14a, and by pressing the switch Sb, the relay R
Since a weak current branched from the variable resistor VR flows through the first solenoid 6 through the axes of the a contact of the limit switch LS and the a contact of the relay R3, a weak attraction force is generated in the first solenoid 6, and this attraction force is accumulated. The lever 4 acts in the opposite direction to the elasticity of the spring 14 to gently lower the gripping rod 1. The descending speed of the presser bar 1 can be adjusted to g by the screw cylinder 14 and the variable resistance VR.

When the presser foot 3 contacts the feed dog and the presser bar 1 reaches the bottom dead center, the base end of the stacking rod 4a contacts the limit switch LS and opens its contact.

As a result, the relay 3 is demagnetized, its contacts open, cutting off the current to the first solenoid 6, and the elasticity of the spring 14 presses the presser foot 3. When the switch Sb is released, the locking rod 11 is returned to its original position by the spring 12.

In this way, in the present invention, the presser bar 1 is pressed downward by the spring 14, the presser bar 1 is raised by the first solenoid 6 against this spring, and then moved in and out by the second solenoid 10 near the top dead center. Since the presser bar 1 is locked by the locking rod 11, the presser bar 1 can be maintained in the raised or lowered position without energizing the first and second lenses 6, 10, reducing power consumption. This has the effect that the solenoid will not burn out, and when the presser bar 1 is lowered, a weaker current is passed through the first solenoid 6 than when the presser bar 1 is raised, reducing the elasticity of the spring 14 and applying braking to the presser bar 1. Therefore, the presser bar 1 descends gently, thereby preventing the presser foot 3 from colliding with the feed teeth or throat plate.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is a circuit diagram thereof. 1 is a presser bar, 6 is a first lenoid, 10 is a second lenoid, 11 is a locking rod, and 14 is a spring. Patent applicant Kowa Precision Machinery Co., Ltd. Agent Tetsube Maki (and 2 others)

Claims (1)

[Claims] The presser bar is moved against the spring by the first solenoid. When the presser bar is raised and near the top dead center, the presser bar is locked to the locking rod that is moved in and out by the second solenoid, and when the presser bar is lowered, a weaker current is passed through the first solenoid than when it is raised. A device for lifting and lowering the presser foot of a sewing machine.