JPS608861Y2 - Sewing machine rotation speed and needle position detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in a rotational speed and needle position detection device for a sewing machine.

Conventionally, the above-mentioned device detects the multipolar magnetic field of a ring magnet that rotates together with the upper shaft of the sewing machine using a detector such as a Hall element, and detects the rotational speed of the sewing machine based on the number of pulses detected in a certain period of time. A known sewing machine is configured to detect the position of a sewing machine needle by detecting the magnetic field of a single-pole magnet that rotates together with the upper shaft of the sewing machine using a detector such as a Hall element.

However, in conventional sewing machine rotational speed and needle position detection devices, the rotational speed detection section and the needle position detection section are configured separately, resulting in a complex structure, and the devices must be installed and adjusted separately. There were drawbacks such as not being able to do so.

Furthermore, when detecting the magnetic field of a ring magnet with a sensing object such as a Hall element, it is necessary to make the gap between the ring magnet and the sensing object as narrow as possible to reduce magnetic flux attenuation. If the structure is such that a multipolar magnetic field magnetized on a surface is detected by a detection body placed on the outer circumferential side of the ring magnet, as mentioned above, it is necessary to narrow the gap between the ring magnet and the detection body, so the dimensional accuracy of the ring magnet is required. It must be processed well.

For this reason, there is a drawback that processing costs are high, such as the need to polish the inner and outer diameters of the ring magnet.

In view of the above-mentioned conventional circumstances, the present invention improves the structure and ease of assembly of the device by structurally configuring the rotational speed detection part and the needle position detection part. The present invention provides an inexpensive detection device in which a multipolar magnetic field magnetized in a direction is detected by a detection body disposed perpendicularly to the multipolar magnetic field, and the gap between the magnet and the detection body can be easily adjusted.

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In these figures, 1 is the sewing machine body, 2 is the upper shaft of the sewing machine,
3 is a pulley for transmitting rotational force to the upper shaft 2 of the sewing machine, and is fixedly attached to the upper shaft 2 of the sewing machine with a 3A set screw.

4 is a magnetic mounting ring made of a non-magnetic material that is fixedly attached to the outer periphery of the tip of the upper shaft 2 of the sewing machine with a set screw 4A as a fixing means; 5 is a ring that is fitted and fixed to the outer periphery of the outer end of the mounting ring 4; The sewing machine is multi-pole magnetized in two directions on the upper shaft.

Reference numeral 6 denotes a single-pole magnet fitted and fixed to the outer end surface of the mounting ring 4, and is magnetized in the two directions of the upper shaft of the sewing machine.

Reference numeral 7 denotes a printed circuit board disposed so as to face substantially the lower half of the outer end surface of the mounting ring 4 in parallel with a predetermined interval, and 8 is provided at a position of the printed circuit board 7 that can correspond to the end surface of the ring magnet 5. , Hall elements 9, 9 for detecting the magnetic field of the ring magnet 5 are provided at positions corresponding to the end surfaces of the monopolar magnet 6 of the printed circuit board 7, and are a pair of Hall elements for detecting the magnetic field of the monopolar magnet 6. be.

A holder 10 fixedly supports the printed circuit board 7 and is attached to the sewing machine body 1 with a fastener 11.

12 is a set screw for attaching the printed circuit board 7 to the holder 10, 13 is a spacer, and 14 is a cover that covers the magnet attachment ring 4 and the printed circuit board 7 portion.

In the rotational speed and needle position detection device configured as described above, the magnet attachment ring 4 rotates when the sewing machine upper shaft 2 rotates.

Then, the position of the magnetic field that crosses the Hall element 8 of the ring magnet 5 changes.

Here, since the Hall element 8 generates a voltage due to the Hall effect when a magnetic field is applied at right angles to it, the number of magnetic fields passing through the Hall element 8, which is proportional to the number of rotations of the sewing machine, is the pulse obtained by the extracted voltage. If we take it as a number, we can know the sewing machine rotation speed by the number of pulses detected within a certain period of time.

On the other hand, the magnetic field of the single-pole magnet 6 is transferred to a pair of Hall elements 9
, 9, the needle position can be detected.

That is, the sewing machine needle (not shown) is connected to the pulley 3, that is, the mounting ring 4.
If the mounting position of the monopolar magnet 6 on the mounting ring 4 is adjusted and set so that the monopolar magnet 6 crosses the Hall elements 9, 9 when the monopolar magnet 6 moves to the lower or upper position according to the rotation of the The lower position signal of the needle can be taken out by generating a voltage in one Hall element 9, and the upper position signal can be taken out by the other Hall element 9.

According to the above configuration, the magnetic field detection structure of the ring magnet 5 detects a multipolar magnetic field magnetized in the direction of the sewing machine upper shaft 2 of the ring magnet 5. It can be formed with high dimensional accuracy by polishing the surface perpendicular to the ring magnet 5, and the gap between the ring magnet 5 and the Hall element 8 can be made uniform and small. It has the advantage that it does not require polishing and the processing cost is low.

In addition, since the Hall element 8 for detecting rotational speed and the Hall elements 9, 9 for detecting needle position are both mounted on the same plane via the printed circuit board 7, these Hall elements 8, 9, 9, ring magnet 5 and single The gap with the pole magnet 6 can be adjusted at the same time, and the structure is simple, wiring, etc. can be printed easily, and assembly is also simple.

As described above, the present invention structurally integrates the rotational speed detection part and the needle position detection part, so the structure and assembly are simpler than conventional detection devices. Since the magnetic force of the magnet is weak, it is extremely important to adjust the gap between each sensing object, but since the mounting ring can be adjusted in position in the direction of the upper axis of the sewing machine, the gap between each magnet and each sensing object can be adjusted. Adjustments can be made easily at the same time, and since the mounting ring is made of non-magnetic material, mutual magnetic interference between the multi-pole ring magnet and the single-pole magnet can be reduced, making it possible to reduce the rotational speed of the inexpensive and reliable sewing machine. This provides the advantage of being able to provide a needle position detection device.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an example of a rotational speed and needle position detecting device for a sewing machine according to the present invention, and FIG. 2 is a side view of the same device. 2... Sewing machine upper shaft, 4... Mounting ring, 4A... Set screw, 5... Multipolar ring magnet, 6... Unipolar magnet, 7...Printed circuit board, 8゜9...Hall element.

Claims (3)

[Scope of utility model registration request] (1) A non-magnetic magnet whose position can be adjusted in the direction of the upper axis of the sewing machine, such as a multi-pole ring magnet and a single-pole magnet magnetized in the direction of the upper axis of the sewing machine, and which are rotatably attached to the upper axis of the sewing machine by a fixing means. It is held in a mounting ring consisting of a body,
A rotational speed detector for detecting the magnetic field of the multipolar ring magnet and a needle position detector for detecting the magnetic field of the single-pole magnet are arranged on the same plane facing the mounting ring,
The sewing machine rotation speed is detected by detecting the number of magnetic fields of a multi-pole ring magnet that crosses the rotation speed detector, and the magnetic field of a single-pole magnet corresponding to the position of the sewing machine needle, which moves up and down according to the rotation of the upper shaft of the sewing machine, is detected. A rotational speed and needle position detection device for a sewing machine, characterized in that it is configured to detect a needle position. (2) The rotational speed and needle position detecting device for a sewing machine according to claim 1, wherein the detecting bodies are each mounted on a printed circuit board. (3) The rotational speed and needle position detecting device for a sewing machine according to claim 1 or 2, wherein the sensing body is a Hall element.