Sewing machine drive equipment

Abstract

A magnetic encoder system (2) for a sewing machine drive comprises a magnetized disk (5), an incremental track (8) and a reference track (9). The incremental track (8) extends around the disk (5) over the entire circumference and has alternating pole parts (10) used as incremental markings. The reference track (9) is designed as a ring segment on the disk (5) and has a single pole (11). The result is a magnetic encoder system (2) for a servomotor of a sewing machine, for example.

Description

Technical Field

[0001] This patent application claims the priority of German patent application DE 10 2017 218 354.3, the content of which is incorporated herein by reference.

[0002] The present invention relates to a sewing machine drive device and a sewing machine with the sewing machine drive device according to the present invention. Background Art

[0003] In particular, DE 197 14 520 A1 and US Pat. No. 5,860,377 A disclose a drive device for a sewing machine. Summary of the invention

[0004] It is therefore the object of the present invention to improve the known prior art so that a drive device for a sewing machine can be produced simply and cost-effectively and can at the same time be operated in a functionally reliable manner.

[0005] This object is achieved by a sewing machine drive device having the following characteristics. According to the invention, a sewing machine drive device with a magnetic encoder system is proposed, comprising: a disk made of magnetic material; an incremental track; and a reference track, wherein the disk is magnetized, the incremental track extends around the disk over the entire circumference and has alternating pole parts serving as incremental markings, and the reference track is designed as a ring segment on the disk and has a single pole.

[0006] The sewing machine drive device according to the present invention has a reference track, which includes a single pole. The term "single pole" refers to the magnetization of the reference track, wherein the magnetic flux density of one pole has a peak value that is much larger in magnitude than the magnetic flux density of the opposite pole, which is then negligible. The ratio of the peak value of the magnetic flux density between the pole that actually works exclusively and the opposite pole that is negligible is at least greater than 5.

[0007] By providing the reference track with at least one single pole, the construction effort is reduced compared to systems known from the prior art. The single-pole construction can reduce errors and inaccuracies when evaluating the detectable signal. Furthermore, due to the single pole provided with the reference track, larger production tolerances can be achieved during the magnetization, which results in a simpler production of the encoder system according to the invention.

[0008] The reference track can be constructed on a magnetic, in particular ferrite disk, wherein the disk can be connected to a shaft, in particular a motor shaft, in a rotationally fixed manner. The single pole of the reference track only includes a partial section in the circumferential direction of the disk. In addition to the reference track, the disk also includes an incremental track, which is designed over the entire circumference of the disk. By providing the reference track with a single pole, the mutual magnetic influence of the incremental track and the reference track is reduced compared to a conventional encoder system. Therefore, an improved functional reliability of the encoder system is guaranteed. In addition, a more compact or smaller design of the encoder system according to the invention is particularly conceivable, because the incremental track and the reference track can be closer to each other without influencing each other.

[0009] Advantageously, the incremental track and the reference track are designed circularly and coaxially with respect to one another. In particular, the reference track has a smaller radius than the incremental track, although the opposite design is also conceivable. At the same time, the tracks can be designed coaxially with respect to the axis. It is also conceivable that the tracks are designed eccentrically with respect to one another and with respect to the axis and / or are designed angularly, in particular polygonally, for example pentagonally or hexagonally.

[0010] The incremental track as well as the reference track can be arranged on the top side and / or the bottom side of the disk and / or on a housing wall of the disk.

[0011] It is also conceivable to use other tracks in addition to the reference track and the incremental track. The other track is advantageously designed as a partial section along the circumference of the disk and is arranged at a different position on the disk than the incremental track and the reference track. Advantageously, the other track has a single pole.

[0012] The detectable signals of these tracks can be supplied to different signal evaluation units. In particular, magnetoresistive sensors, advantageously Hall sensors, are used to evaluate the detectable signals.

[0013] A sewing machine drive device with an encoder system can achieve optimized controllability of the drive device, especially the sewing machine motor, thereby facilitating the operation of the sewing machine.

[0014] An encoder system is known from DE 10 2015 226 666 A2. Other encoder systems are known from US 2016 / 0146630 A1, DE 3990 206 T5, DE 10 2011 053 309 A1, US 2015 / 0091554 A1 and US 4,551,676 A.

[0015] A sewing machine drive device according to one embodiment can achieve reduced errors and inaccuracies when analyzing detectable signals. Crosstalk between the incremental track and the reference track, especially caused by the magnetic field, is avoided. According to a particularly advantageous design, the disk has a recess between the incremental track and the reference track, which is configured to surround the entire circumference. Alternatively, the recess can also be configured as a ring segment on the disk. Advantageously, the recess is configured at the following section on the disk: the reference track is configured at this section. Here, the section-recess on the disk extends the same circumferential extension length as the reference track. The recess can be used to create an air gap between the incremental track and the reference track, thereby suppressing undesirable influences of the two tracks.

[0016] According to one embodiment, the monopole has a magnetic flux density in the first region which is at least 10 times greater than the magnetic flux density in at least one second region. The sewing machine drive device according to the above embodiment enables reliable and interference-free determination of the reference track by a corresponding signal analysis unit. In particular, the magnetic field strength or magnetic flux density in the first region is 15 to 25 times greater than the magnetic field strength or magnetic flux density in the second region, advantageously 20 times greater.

[0017] According to one embodiment of the sewing machine drive device, the reference track can be reliably and without interference determined by a corresponding signal evaluation unit. In particular, the monopole can extend along the circumference of two or more pole parts of the incremental track. Advantageously, the monopole extends along the circumference of the pole parts of the incremental track.

[0018] According to one embodiment, a sewing machine drive device can realize steering recognition. The number of monopoles can be changed here. In particular, two or more monopoles are arranged on the reference track, advantageously four monopoles are arranged, but multiple monopoles can also be considered. Advantageously, the monopoles - regardless of their number - are equidistant in the circumferential direction of the reference track. In addition, in particular with respect to the circumference of the pole parts of the incremental track, the monopoles can have different circumferential extension lengths. In a particularly advantageous design of the reference track, the circumferential extension length of the next monopole is increased from the first monopole by the circumferential extension length of the other pole part of the incremental track.

[0019] According to one embodiment, a sewing machine drive is used for zero-point referencing of a rotor, whereby a detectable signal can be synchronized, in particular in the case of a plurality of single poles on a reference track, with a machine control system to which the magnetic encoder system is coupled. The machine control system is in particular a sewing machine control system.

[0020] In one embodiment of a sewing machine drive, the detectable signal is evaluated by an evaluation unit having an integrated microcontroller and a magnetic sensor, thereby providing a particularly compact encoder system.

[0021] According to one embodiment, a sewing machine drive device can achieve independent zero point reference.

[0022] According to the invention, a sewing machine is provided which has the above-described sewing machine drive device. The advantages of the sewing machine correspond to the advantages already described above with reference to the sewing machine drive device according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0024] Figure 1 A three-dimensional illustration of an encoder system component assembly for mounting on a servomotor of a sewing machine;

[0025] Figure 2 A three-dimensional top view of the encoder system-component group;

[0026] Figure 3 is a perspective detailed view of a magnetic encoder system according to a first embodiment;

[0027] Figure 4 Based on Figure 3 A magnified view of the magnetic encoder system in the unipolar region;

[0028] Figure 5 Based on Figure 3 A curve diagram showing a change in the magnetic flux density B of a reference track of a magnetic encoder system;

[0029] Figure 6 Based on Figure 3 A cross-sectional view of a magnetic encoder system;

[0030] Figure 7 is a perspective detailed view of a magnetic encoder system according to a second embodiment. DETAILED DESCRIPTION

[0031] Below, refer to Figures 1 to 6 , a first embodiment of a magnetic encoder system for a sewing machine in the form of a sewing machine servo motor is described.

[0032] Figure 1 and Figure 2 An encoder system component set 1 is shown for fastening a magnetic encoder system 2 to a servomotor of a sewing machine. For the sake of clarity, the servomotor is not shown, but its position is indicated by a motor shaft 4 with an axis 4a. In addition to the magnetic encoder system 2, the component set 1 also includes a mounting flange 3, by means of which the magnetic encoder system 2 is fastened to the servomotor. The mounting flange 3 and the magnetic encoder system 2 each have an opening starting at their center, by which they are mounted on the motor shaft 4 of the servomotor. These openings are designed to be circular.

[0033] The magnetic encoder system 2 comprises an annular disk 5 made of a magnetic, in particular ferrite, material. The disk 5 is connected to the motor shaft 4 in a rotationally fixed manner, so that a rotation of the motor shaft 4 simultaneously causes a rotation of the disk 5 .

[0034] The mounting flange 3 has a plate 6 on its side facing the disk 5, by means of which an evaluation unit 7 is fixed to the mounting flange 3. The evaluation unit 7 is used to read out the incremental track 8 and the reference track 9 arranged on the disk 5. The mounting flange 3 and the evaluation unit 7 located thereon are designed to be fixed in position. This means that a rotation of the motor shaft 4 does not lead to a rotation of the mounting flange 3 and the evaluation unit 7.

[0035] Depend on Figure 3 The magnetic disk 5 according to the first exemplary embodiment can be seen. The incremental track 8 and the reference track 9 are circular in design and extend along the circumference of the magnetic disk 5, wherein the incremental track 8 is arranged on the circumference over the entire circumference, while the reference track 9 comprises only a part of the circumference. The incremental track 8 has alternating pole sections 10. In contrast, the reference track 9 comprises exactly one single pole 11. The two tracks 8, 9 are arranged coaxially to each other and to the motor shaft 4. In this case, the reference track 9 has a radius R A , which is smaller than the radius R of the incremental track 8 V .

[0036] The evaluation unit 7 is mounted on the mounting flange 3 via a plate 6 opposite the disk 5 and serves to read out the incremental track 8 as well as the reference track 9. The evaluation unit 7 is arranged so that a first magnetic sensor detects the incremental track 8 and a further magnetic sensor detects the reference track 9. The two magnetic sensors are arranged radially offset from each other and are not shown in the figure for the sake of clarity.

[0037] Depend on Figure 4 From the enlarged view of the magnetic encoder system in FIG. 1 , it can be seen that the monopole 11 of the illustrated embodiment can be understood as a structure of a pole part 10 having a south pole S extending in the circumferential direction of the reference track 9, which is defined by two opposing and weakly expressed quasi-North Pole segments N'. The two quasi-North Pole segments N' represent the opposite poles of the south pole S and together form the monopole 11. The structure of the monopole 11 can also be understood as follows: the south pole S is composed of two south pole segments, each of which includes one of the quasi-North Pole segments N'. In the region of the south pole S, there is a strong magnetic field strength H or magnetic flux density B, while in the region of the quasi-North Pole segment N', there is only a very weak magnetic field strength H or magnetic flux density B.

[0038] Figure 5The curve diagram shown in FIG. 1 shows a smooth variation curve diagram of the magnetic flux density B (y-axis) along the circumferential extension length (x-axis) of the reference track 9 according to the first embodiment. In the non-magnetized area of ​​the reference track 9, the magnetic flux density B cannot be measured beyond the monopole 11. In the circumferential area of ​​the quasi-North Pole section N' of the monopole 11, the magnetic flux density B 2 The maximum value is designed to be greater than the magnetic flux density B in the circumferential extension length region of the south pole S of the monopole 11. 1 According to the embodiment shown, the magnetic flux density B 1 The corresponding magnetic flux density B is numerically 2 23 times. 1 | / |B 2 The ratio of | can be greater than 10, greater than 15, greater than 20, or greater than 23.

[0039] Figure 6 The disk 5 of the magnetic encoder system 2 is shown in a sectional view. The disk 5 has a recess 12 in the circumferential direction between the reference track 9 and the incremental track 8. In the exemplary embodiment shown, the recess 12 is designed to run around the entire circumference and serves to produce an air gap between the incremental track 8 and the reference track 9. This suppresses mutual influence of the two tracks 8 and 9. In particular, crosstalk caused by the magnetic field between the two tracks 8 and 9 is effectively prevented.

[0040] Refer to the following Figure 7 The second embodiment of the magnetic encoder system according to the present invention for a sewing machine drive device is introduced. The same parts are marked with the same figure marks as the first embodiment, and here refer to the description of the first embodiment. The main difference compared to the first embodiment is that a plurality of monopoles 11 are constructed along the circumferential direction on the reference track 9. These monopoles 11 are arranged 90° apart from each other. It is also conceivable that, instead of four monopoles 11, different numbers of monopoles 11 are arranged on the reference track 9. The monopoles 11 of the reference track 9 have the circumferential extension length of the pole parts 10 of the incremental track 8. However, the circumferential extension lengths of these monopoles 11 can be different from each other.

[0041] Different, not shown, variants of the encoder system assembly 1 are conceivable. The incremental track 8 can be arranged, for example, on the top side of the disk 5, and the reference track 9 can be arranged on the bottom side of the disk 5. The incremental track 8 and / or the reference track 9 can also be arranged on the housing wall of the disk 5.

Claims

1. A sewing machine driving device having a magnetic encoder system (2), comprising: - a disk (5) made of magnetic material; - Incremental track (8); and - reference track (9), - wherein the disk (5) is magnetized, wherein the incremental track (8) extends completely around the disk (5) and has alternating pole elements (10) serving as incremental markings, -Wherein, the reference track (9) is designed as a ring segment on the disk (5), characterized in that the reference track (9) has a single pole (11) which has a magnetic flux density B1 in a first region which is at least 10 times the magnetic flux density B2 in at least one second region.

2. The sewing machine driving device according to claim 1, characterized in that: The disk (5) has a recess (12) between the incremental track (8) and the reference track (9).

3. The sewing machine driving device according to claim 1 or 2, characterized in that: The monopole (11) has a magnetic flux density B1 in the first region which is at least 15 times greater than a magnetic flux density B2 in at least one of the second regions.

4. The sewing machine driving device according to claim 3, characterized in that: The monopole (11) has a magnetic flux density B1 in the first region which is at least 20 times greater than a magnetic flux density B2 in the second region.

5. The sewing machine driving device according to claim 1 or 2, characterized in that: The monopole (11) extends along the circumference of at least one pole section (10) of the incremental track (8).

6. The sewing machine driving device according to claim 1 or 2, characterized in that: The reference track (9) has a plurality of monopoles (11) in the circumferential direction.

7. The sewing machine driving device according to claim 1 or 2, characterized in that: The reference track (9) is used for zero point reference.

8. The sewing machine driving device according to claim 1 or 2, characterized in that An evaluation unit (7) has an integrated microcontroller and a first magnetic sensor for detecting the incremental track (8).

9. The sewing machine driving device according to claim 1 or 2, characterized in that A further, separate magnetic sensor is used to detect the reference track (9).

10. A sewing machine having the sewing machine driving device according to claim 9.

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