EP1582617A1 - Sewing machine - Google Patents

Abstract

A sewing machine has a base plinth with an upright column supporting a horizontal overhead arm containing a motor-driven shaft with a rotor (40) and a stator (33). The rotor (40) has a rotor body (41) with a cylindrical outer wall (52). The rotor body has a number of embedded permanent rectangular magnets (46). The rotor (41) outer wall edge (53) has a series of concave detents (54), each of which engages with a matching opposite protrusion (53). The concave detents (54) are grooves or circle sectors. The depth (T) of the concave detents (54) is comparable with the rotor residual thickness (S) between the detent (54) and the sockets for the permanent magnets (46). The depth is between one half and twice that of the residual thickness.

Description

Such a sewing machine is known from DE 199 61 201 A1. To This known sewing machine similar sewing machines are known from DE 41 12 597 B4, DE 32 49 227 T1 and DE 72 20 868 U1. If the rotor is to be turned by hand in the known sewing machine, so must at certain Retativ angular positions of the rotor to the stator an increased force is expended. This is undesirable. simultaneously exists in the known sewing machines the risk that the rotor, starting from a certain, manually given relative angular position between rotor and stator, automatically to another relative angular position shifted, which is also undesirable. Known attempts this increased effort at certain relative angular positions or to eliminate this propensity for restitution, are constructive very expensive.

It is therefore the object of the present invention, a sewing machine of the type mentioned in such a way that by hand a predetermined Relative angular position between rotor and stator light and is defined adjustable, in particular, no unwanted adjustment the once set relative angular position to take place.

This object is achieved by a sewing machine with the features specified in the characterizing part of claim 1.

The inventive shape of the outer wall of the rotor body leads to that the magnetic flux in the edge regions of the permanent magnet compared to the other outer wall areas so influenced, in particular is weakened that in the rotor without energization of the electric motor resulting torques are reduced. This leads to a Equalization of the applied force, if by hand set a certain relative angular position between the rotor and stator shall be. This homogenization of the magnetic flux At the same time, this leads to an unwanted relocation of a once adjusted relative angular position does not take place. Even if via the electric motor drive a predetermined relative angular position set and held between rotor and stator should, the inventive solution is advantageous because the necessary holding currents reduced to maintain the predetermined relative angular position are.

Recesses according to claim 2 can be manufactured with little effort.

A dimensioning of the Ausnchmungstiefe to the remaining rotor body thickness according to claim 3 has as for the homogenization of the magnetic Flux density proved particularly advantageous.

A numerical ratio of the number of pole pieces to the number of permanent magnets according to claim 4 additionally leads to a homogenization of for relative angle adjustment force required and to Reduction of unwanted tendency to adjust.

Four permanent magnets according to claim 5 or twelve pole pieces according to claim 6 have in the structural design of the electric motor proved to be particularly advantageous.

Permanent magnets according to claim 7 lead to a defined field line course.

Fig. 1

eine Seitenansicht einer Nähmaschine aus Sicht eines Bedieners;

Fig. 2

einen Schnitt gemäß Linie II-II in Fig. 1;

Fig. 3

einen vergrößerten Ausschnitt gemäß Linie III-III in Fig. 2;

Fig. 4

eine perspektivische, vergrößerte Ansicht eines Handrads der Nähmaschine nach den Fig. 1 bis 3;

Fig. 5

das Handrad nach Fig. 4 aus einer anderen Perspektive;

Fig. 6

vergrößert einen Schnitt gemäß Linie VI-VI in Fig. 3;

Fig. 7

vergrößert einen Rotorkörper eines in Fig. 6 dargestellten Armwellen-Antriebsmotors;

Fig. 8

einen Permanentmagneten des Rotors des Armwellen-Antriebsmotors in einer Stimansicht;

Fig. 9

eine perspektivische Ansicht des Permanentmagneten nach Fig. 8;

Fig. 10

eine AusschnittsvergröBerung der Darstellung nach Fig. 6;

Fig. 11

vergrößert einen Schnitt gemäß Linie XI-XI in Fig. 3;

Fig. 12

einen Statorkörper des Armwellen-Antriebsmotors in einer Stirnansicht; und

Fig. 13

eine zu Fig. 3 ähnliche Darstellung einer weiteren Ausführung einer Nähmaschine.

Embodiments of the invention will be explained in more detail with reference to the drawing. In this show:

Fig. 1

a side view of a sewing machine from the perspective of an operator;

Fig. 2

a section along line II-II in Fig. 1;

Fig. 3

an enlarged section along line III-III in Fig. 2;

Fig. 4

an enlarged perspective view of a handwheel of the sewing machine of Figures 1 to 3.

Fig. 5

the handwheel of Figure 4 from a different perspective.

Fig. 6

enlarges a section along line VI-VI in Fig. 3;

Fig. 7

enlarges a rotor body of a arm shaft drive motor shown in FIG. 6;

Fig. 8

a permanent magnet of the rotor of the arm shaft drive motor in an end view;

Fig. 9

a perspective view of the permanent magnet of Fig. 8;

Fig. 10

a detail enlargement of the representation of FIG. 6;

Fig. 11

enlarges a section along line XI-XI in Fig. 3;

Fig. 12

a stator body of the arm shaft drive motor in an end view; and

Fig. 13

an illustration similar to Fig. 3 of another embodiment of a sewing machine.

The sewing machine 1 shown in FIGS. 1 to 13 comprises a box-like Base plate 2, an upper arm 3 and connecting them Stand 4. The sewing machine 1 is thus formed a total of approximately C-shaped. In the arm 3, an arm shaft 5 is mounted, via which a needle bar. 6 with a needle 7 by means of a crank drive not shown in detail can be driven up and down. From the arm shaft 5 is connected via a Belt drive 8 and mounted in the base plate 2 shaft 9 in the Base plate 2 stored and the needle 7 associated gripper driven, which is also not shown in detail.

A flange portion 10 is on the arm shaft 5 at the level of the belt drive 8 arranged. About the flange portion 10, the arm shaft 5 with a for this purpose aligned drive shaft 11 of a arm shaft drive motor 12th rotatably connected. Adjacent to the flange portion 10 is the drive shaft 11 supported by an axial / radial bearing 12a. On a free end 13 the drive shaft 11 is a handwheel 14 attached and a radial screw 15 rotatably connected to the drive shaft 11. The radial screw 15 is screwed into a hand wheel carrier body 16, the in turn attached to the free end 13 of the drive shaft 11. about a total of three mounting screws 17, which in the circumferential direction around a Longitudinal axis 18 of the drive shaft I1 distributed and parallel to this are arranged extending, is the handwheel 14 with the handwheel carrier body 16 bolted.

Perspective, enlarged views of the handwheel 14 are shown in FIG. 4 and 5. An operating portion 19 of the handwheel 14 is free from outside accessible circumferential collar configured. This is based on a cylindrical outer boundary wall 20 of the handwheel 14. Between the outer Boundary wall 20 and a spaced therefrom inner boundary wall 21 of the handwheel 14, a fan 22 is arranged, which the cooling of the arm shaft drive motor 12 is used. The fan wheel 22 has a total of twelve fan blades 23. The fan 22 is in Handwheel 14 housed. Between the boundary walls 20, 21 is defines an annular space in which the fan blades 23 partially arranged are. Each of the fan blades 23 is integral with both the inner boundary wall 20 and connected to the outer boundary wall 21. The fan blades 23 are where they are integral with one within the Operating portion 19 arranged, dome-shaped outward tapering end portion 24 of the outer boundary wall 20 pass over obliquely with respect to radial surfaces to the longitudinal axis 18 employed. in the Course inside are the fan blades 23 within the end portion 24th bent in an inner arc portion 25 so that the inner ends the arcuate portions 25 extend approximately radially to the longitudinal axis 18.

In the circumferential direction about the longitudinal axis 18, every fourth fan blade 23 an integrally formed on this screw 26, in the with mounted handwheel 14 each one of the three mounting screws 17th is included. The fan blades 23 go to the drive motor 12 radially in one piece in the inner boundary wall 21 of the handwheel 14th above. The inner boundary wall 21 widens conically to the drive motor 12 out. An Anschraubwand 27, the part of the inner boundary wall 21, lies flat against a peripheral collar 28 of the handwheel carrier body 16 on. In the circumferential collar 28 are the threads for screwing the fastening screws 17 executed. Toward the drive motor 12 is the free end of the inner boundary wall 21 together with the over these protruding ends of the fan blades 23 on a guide cap 29, which is also rotatably connected to the drive shaft 11.

At the height of the guide cap 29 is a positioning wheel with the drive shaft 11 30, which has a plurality of position markings wearing. In a peripheral region, the positioning wheel 30 dips into a sensor slot a housing-mounted rotary encoder 31 a. Of the Rotary signal generator 31 provides position information about the current rotational position the drive shaft 11 to a not shown in the drawing Control device of the sewing machine 1 on. The rotary signal generator 31 is attached to a housing-mounted mounting plate 32. Along the drive shaft 11 inwardly, ie towards the arm shaft 5, the holding plate 32 is a stator 33 of the drive motor 12 downstream. The holding plate 32 has an opening 34 for the drive shaft 11.

The stator 33 is in a hollow cylindrical recess 35 of a motor housing 36 arranged, which is part of the sewing machine housing and is completely disposed within the sewing machine housing. The motor housing 36 is integrally formed in the sewing machine housing. In the circumferential direction distributed around the stator 33 and adjacent to this has the Motor housing 36 a plurality of air ducts 37 which are parallel extend to the longitudinal axis 18. The section of Fig. 2 shows the air ducts 37 in frontal view. The air ducts 37 are as longitudinal grooves in the stator 33 facing inner wall of the motor housing 36th executed. In the section of FIG. 3, the air ducts 37 are shown by dashed lines Lines indicated. Via openings 38 at the level of the holding plate 32 are the air ducts 37 to the fan 22 back with the of the outer boundary wall 20 of the handwheel 14 to the outside and the inner Limiting wall 20 and the guide body 29 limited to the inside Annular space connected. This annulus is used for cooling air flow between the fan 22 and the air ducts 37. The other End of the air ducts 37 opens in the region of the flange 10 in the Interior of the sewing machine 1 off. In the air ducts 37 are metal strips 38a inserted, which has an outwardly sealed fluid connection between the through holes 38 and the interior of the sewing machine. 1 create in the region of the flange portion 10.

The longitudinal extent of the stator 33 is less than that of the motor housing 36. The metal strips 38a prevent over the over the stator 33 projecting portions of the air ducts 37 on both sides of the stator 33 a connection of the air ducts 37 to two annular communication spaces 39 is given. A dust entry into the arm shaft drive motor 12 is prevented. The rotor 40 is in turn rotationally fixed connected to the drive shaft 11. In Fig. 3 right next to the rotor body 41 is a ring-shaped the drive shaft 11 surrounding balancing body 40a rotatably connected to the drive shaft 11. The balancing body 40a carries not shown balancing weights for balancing the drive shaft 11. A rotor body 41 of the rotor 40 has a total four recesses 42 to 45, each for receiving one Permanent magnets 46 are formed. The recesses 42 to 45 in the Rotor body 41 open at the end faces of the rotor 40 via one Receiving opening 45a. The receiving openings 45a are mounted Rotor 40 in Fig. 3 to the left via a step in the drive shaft eleventh and closed in Fig. 3 to the right over the balancing body 40a.

A permanent magnet 46 is shown in FIGS. 8 and 9. The permanent magnet 46 is formed as a flat cuboid, wherein the magnetic poles of the permanent magnet 46 are arranged such that in the permanent magnet 46 the field lines vertically between the two in terms of area largest side walls 47, 48 of the permanent magnet 46 extend. Of the Course of the magnetic field lines between the magnetic poles South and north of the permanent magnet 46 is shown in Fig. 8 by an arrow 49th indicated. Through this course, the magnetic orientation of the Permanent magnets 46 fixed.

In the side wall 47 shown in Fig. 8 above, the permanent magnet 46 a longitudinal groove 50 with arc or part-circular base. Complementarily, each of the recesses 42 to 45 has a protruding Longitudinal nose 51 on. This nut-and-nose mating forces that of the Permanent magnet 46 in one of the recesses 42 to 45 only inserted can be that the north pole of the permanent magnet of the Longitudinal nose 51 faces. The permanent magnets 46 can therefore in their associated recesses 42 to 45 only in exactly one magnetic Orientation to be included.

Alternative to the illustrated embodiment, other asymmetric and mutually complementary embodiments of the forms of Permanent magnet 46 on the one hand and the recesses 42 to 45 on the other possible to ensure that each permanent magnet 46 in the associated recess 42 to 45 in exactly one magnetic Orientation is included. For example, the permanent magnet 46 have a nose in a complementary groove of the recesses 42 to 45 intervenes. In other variants complementary to each other asymmetric pairings of permanent magnets on the one hand and recesses on the other hand can be perpendicular to the insertion direction the permanent magnets complementary cross-sectional geometries the permanent magnet on the one hand and the recesses on the other present, the rotation of the permanent magnet to the insertion direction do not merge into each other by 180 °.

As shown in FIGS. 6 and 7, the four permanent magnets 46 are in FIG the recesses 42 to 45 within the hollow cylindrical rotor body 41 in the circumferential direction about the longitudinal axis 18 in each case by 90 ° offset from one another arranged such that the largest in terms of area side walls 47, 48 of the permanent magnets 46 with chordal planes one of an outer wall 52 of the rotor body 41 predetermined cylindrical surface coincide. The longitudinal projections 51 in the orientation of the rotor body 41 according to FIGS. 6 and 7, top and bottom recesses 42, 44 are centered outside and the longitudinal noses of the other two recesses 43, 45 centered inside.

Due to the cuboid shape of the permanent magnet 46 and the complementary thereto Recesses 42 to 45 and due to the described Tendon arrangement of the recesses 42 to 45 in the rotor body 41 are outer edge portions 53 of the permanent magnets 46 adjacent to the outer wall of the rotor body 41. Altogether there are eight such edge regions 53 before. In areas of the outer wall 52, these edge areas 53 are adjacent, has the outer wall 52 of the rotor body 41st concave longitudinal recesses 54. Altogether there are eight longitudinal recesses 54 ago. Each of the longitudinal recesses 54 is one of the eight edge regions 53 assigned.

The longitudinal recesses 54 extend along the entire rotor body 41 parallel to the longitudinal axis 18. The longitudinal recesses 54 are as grooves with formed arcuate or part-circular base. They have a depth T on the remaining strength S of the rotor body 41 between the. Longitudinal recesses 54 and the receptacles 42 to 45 is comparable (see Fig. 7).

The further construction of the drive motor 12 is shown in FIGS. 3, 6, 11 and 12 shown. A stator body 55 of the stator 33 has a total of twelve pole pieces 56, which the outer wall 52 of the rotor body 41 in the circumferential direction Surrounded about the longitudinal axis 18 evenly distributed. The pole shoes 56 are associated with excitation windings 57 (see Fig. 3).

The number of pole shoes 56 of the stator 33 is greater than the number of Permanent magnets 46, namely three times as large. Alternatively, there are others Numbers of pole shoes on the one hand and permanent magnets on the other possible. Preferably, the number of pole shoes is greater than that Number of permanent magnets. The number of pole shoes can be, for example also twice as large as the number of permanent magnets.

The attachment of the stator body 55 to the motor housing 36 is shown in detail in FIG the detail enlargement of FIG. 11 is shown. The stator body 55 has three frontally three circumferentially about the longitudinal axis 18 evenly distributed arranged flange portions 58 which radially over the stator body 55 survive. The flange portions 58 each have a through hole 59. Through each of the through holes 59 is a fastening screw 60 inserted, each in a parallel to the longitudinal axis 18th extending screw in the motor housing 36 is screwed. in the Section of Fig. 3 is the attachment over the lower mounting screw 60 not shown.

A in the drive motor 12 extending magnetic flux through the stator 33 and the rotor 40 is shown in FIG. 10 by way of example with reference to two magnetic Field lines a, b shown. The closed field line b is completely within the closed field line a. The course of the field lines a, b is subsequently in the flow direction according to the directional arrows 49 described in the permanent magnet 46:

The penetrating into the rotor body 41 field lines a, b pass in further course a first of the permanent magnet 46, in the recess 42 lies. The magnetic polarity of this permanent magnet 46 is thus such that its magnetic flux 49 inwardly into the rotor body 41 shows. The emerging from this first permanent magnet 46 Field lines a, b then arcuately pass through the rotor body 41 and subsequently enter from inside to the left adjacent in Fig. 10 Permanent magnet 46 a. This lies in the recess 45, so it has a magnetic polarity that causes its magnetic flux 49 is directed out of the rotor body 42 out. The two field lines a, b occur from this second permanent magnet in the edge region 53 of this out. Due to the present there in the outer wall 52 longitudinal recess 54, the path of the inner field line b runs through a due the longitudinal recess 54 enlarged air gap in the space between the rotor body 41 and the stator body 55. The longitudinal recess 54 causes an increase in the distance of the field lines a, b to each other in comparison to a flow situation in the edge region 53 without the longitudinal recess 54. Due to the longitudinal recess 54 is the distance between the field lines a, b to each other largely independent of whether the gap between the rotor body 41 and the stator body 55 in the edge region 53 or spaced to pass through this becomes. An increase in the magnetic flux in the edge region 53 in FIG Compared to the other sections of the outer wall 52 is therefore practically avoided or largely by the longitudinal recesses 54 reduced. In the further course, the field lines a, b penetrate over a first Pole shoe 56 in the stator 55 and leave this through the right adjacent pole piece 56.

In the idle state of the drive motor 12, ie in the non-energized state the excitation windings 57, performs the described equalization of Flux density in the region of the longitudinal recesses 54 to the rotor 40 in the stator 33 easily by hand in a certain relative angular position can be rotated about the longitudinal axis 18. In a relative angular position of the rotor 40 to the stator 33, in which certain edge regions 53 are adjacent to the pole pieces 56, must in comparison to other Angular positions no particularly increased torque overcome by hand become. An adjustment of the rotor 40 in the idle state of the drive motor 12 from a manually set relative position between Rotor 40 and stator 33 in a displaced and due to an inhomogeneity position forced by the magnetic flux does not take place.

During operation of the drive motor 12 is integrated over the in the handwheel 14 Fan 22 Cooling air from the outside via the annulus between the Boundary walls 20, 21 and the air ducts 37 fed to the stator 22. Cooling air flows along the entire air ducts 37 on the outside of the stator body 55 over. This results in an effective direct cooling of the stator 33 and effective indirect cooling of the rotor 40.

Another embodiment of a sewing machine 1 is shown in FIG. This is described below only where they differ from the Execution of the sewing machine according to FIGS. 1 to 12 differs. components which correspond to those referred to above with reference have been described to Figs. 1 to 12, carry the same reference numerals and will not be explained again in detail.

Instead of an aligned with an arm shaft drive shaft as in the Embodiments of FIGS. 1 to 12, the embodiment of FIG. 13th a continuous arm shaft 61. In a left in Fig. 13 arm shaft section 62, which is the arm shaft 5 of the embodiment of FIGS. 1. 12, the arm shaft 61 of FIG. 13 has the same thickness as FIG the arm shaft 5 of FIGS. 1 to 12. At the height of the axial / radial bearing 12a, the arm shaft 61 tapers over a step 63. A to the step 63 in Fig. 13 right subsequent further arm shaft portion 64 corresponds the drive shaft 11 of the embodiment according to FIGS. 1 to 12. Die Arm shaft 61 is in the region of the flange portion 10 and the drive motor 12 arranged in a carrier sleeve 65. The outer contour of the carrier sleeve 65 corresponds to that of the drive shaft 11 of the embodiment according to 1 to 12. The carrier sleeve 65 is rotatably connected to the arm shaft 61. The carrier sleeve 65 carries the rotatably connected thereto rotor 40th

Claims (7)

Sewing machine (1) with a base plate (2). with an upper arm (3) in which a driven arm shaft (5; 61) is mounted, with a base (4) connecting the base plate (2) and the upper arm (3), wherein the drive of the arm shaft (5: 61) is formed in particular directly by an electric motor (12) located in the stator (4) with a rotor (40) and a stator (33), wherein the rotor (40) rotatably connected to a motor drive shaft (11; 61) has a rotor body (41) with an outer wall (52) of cylindrical basic shape and a plurality of permanent magnets (46) received in the rotor body (41), characterized in that the outer wall (52) of the rotor body (41) has concave recesses (54) in outer wall regions, which edge regions (53) of the cuboidal basic shape have permanent magnets (54), one concave recess (54) being one of the outer walls (52) is associated with adjacent edge region (53). Sewing machine according to claim 1, characterized in that the concave recesses (54) are formed as grooves with arcuate or part-circular base. Sewing machine according to claim 1 or 2, characterized in that the concave recesses (54) have a depth (T) corresponding to the remaining thickness (S) of the rotor body (41) between the recesses (54) and receiving recesses (42 to 45 ) is comparable for the permanent magnets (46), wherein in particular the depth (T) is between half and twice the remaining thickness (S). Sewing machine according to one of claims 1 to 3, characterized in that the number of pole pieces (56) of the stator (33) is greater than the number of permanent magnets (46), preferably more than twice as large and more preferably three times as large. Sewing machine according to one of claims 1 to 4, characterized by four circumferentially around the drive shaft (11) arranged permanent magnet (46). Sewing machine according to one of claims 1 to 5, characterized by twelve pole shoes (46) arranged around the drive shaft (11) in the circumferential direction. Sewing machine according to one of claims 1 to 6, characterized in that the permanent magnets (46) are formed as flat cuboids, wherein the magnetic poles of the permanent magnets (46) are arranged such that the field lines (49, a, b) in the permanent magnet ( 46) extend substantially perpendicularly between the two largest lateral walls (47, 48) of these.

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