EP3556923B1 - Sewing machine - Google Patents

Description

Such a sewing machine is known from the EP 2 975 169 B1 and the EP 2 105 526 B1 . The CN 202658372 U discloses a sewing foot fan device, comprising a stepper motor which interacts with other components of the fan device via a cam disk. The JP 07-231 991 A discloses a presser foot drive sewing machine. The EP 2 351 881 A1 discloses a multi-head embroidery machine with a gear for a presser of a presser unit. The US 2018/0016722 A1 discloses a sewing machine. From the DE-PS 292 059 a presser foot lifting device for sewing machines is known. The JP S56 31787 A discloses a presser foot assembly that cooperates with a cam having a plurality of cam sections.

The object of the present invention is to increase the operational reliability of a common drive for a pressure setting device on the one hand and a fan device on the other hand.

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

One out of the EP 2 975 169 B1 fundamentally known common drive for the pressure setting device on the one hand and for the fan device on the other hand leads to a significant simplification of the sewing machine design. One drive can be saved. Associated control components can also be saved. The common drive can be designed so that this does not fundamentally affect independent functions "foot lifting" and "pressure setting" leads. By saving the drive, the overall construction becomes more cost-effective and compact. By designing the cam lever with two separate scanning bodies, each of which cooperates with the cam plate in at least a section of a total pivoting path, it can be ensured that a motion transmission between the cam plate and the cam lever takes place safely. Unfavorable directions of power transmission during power transmission between the cam and the respective sensing element of the cam lever can be avoided. This can prevent an undefined release of the cam lever from the cam disc. The scanning bodies can be components that are separate from the other cam lever and are firmly connected to it. Alternatively, the scanning bodies can be sections of the cam lever itself. The cam disc can have exactly one curve with which the two sensing elements interact. In this case, the two scanning bodies can interact with different curve sections of one and the same curve of the cam disk.

A simultaneous interaction of the sensing element of the cam lever with the cam plate according to claim 2 can ensure a particularly secure frictional connection between the cam lever and the cam plate. In the section of the total swiveling path of the cam, in which the two scanning bodies cooperate with the cam at the same time, "foot lifting" can take place in a drive area. There it can then be prevented that the cam lever undesirably loses its non-positive connection to the cam disc, for example when thick material is placed underneath, and an undefined state of the common drive can thus be avoided.

An embodiment of a curve of the cam plate according to claim 3 leads to a particularly secure non-positive connection between the cam lever and the cam plate in a section of a total pivoting path of the cam plate. In such an embodiment, the two scanning bodies can encompass a region of the convex curve section. In this way, a positive locking contribution of a power transmission connection between the cam lever and the cam disc can be generated. The two scanning bodies can interact with the convex curve section in the manner of two intermeshing gear wheel sections.

An embodiment of the scanning body according to claim 4 is inexpensive and reliable.

An interaction of the cam disc and cam lever according to claim 5 leads to an advantageous decoupling of mechanical transmission elements for foot lifting on the one hand and for the pressure setting on the other.

A specification of a cam lever position "minimum hold-down pressure" according to claim 6 enables a defined specification of the minimum hold-down pressure.

A fan shaft according to claim 7 makes it possible to arrange the drive away from the presser foot. Seen in a plane perpendicular to the fan shaft, the scanning bodies can be arranged between the fan shaft and the drive shaft of the common drive. Such an arrangement can simplify curve design of the cam disk.

A stepper motor according to claim 8 allows in particular a gradation of the hold-down pressure to be specified. This can be used to adapt to the respective sewing environment. A fine gradation of a fan height is also advantageous. When sewing thick fabrics, a high fan height can be preset. When sewing thinner fabrics, a lower fan height can be preset.

An arrangement of the drive can be such that a drive shaft of the drive, in particular of the stepping motor, either towards the presser foot of the sewing machine or alternatively can be such that the drive shaft is oriented in the direction away from the presser foot. Depending on the installation space requirements for the drive in the transverse or longitudinal direction, for example of a sewing machine arm, a drive which is compact in a critical dimension can hereby be realized.

An adjustment range according to claim 9 enables a fine specification of the hold-down pressure without too great demands on a positioning accuracy or step division for the drive. Such a large adjustment range enables a drive with low torque and at the same time a slight slope of the curve of the cam disc.

It was also recognized that a cam lever with two separate sensing elements and a cam plate shaped accordingly can also be used as a retrofit module. In this way, an already existing drive with a cam lever with exactly one scanning body can be replaced by a drive according to the invention with two scanning bodies, which leads to a correspondingly safe power transmission between the cam lever and the cam.

Fig. 1

perspektivisch eine Nähmaschine in einer Vorderansicht;

Fig. 2

ebenfalls perspektivisch eine Baugruppe der Nähmaschine nach Fig. 1 mit einer Andruck-Einstelleinrichtung zur Vorgabe eines Niederhaltedrucks, den ein Nähfuß beim Niederhalten auf Nähgut ausübt, mit einer Lüftereinrichtung zum Lüften des Nähfußes und mit einem gemeinsamen Antrieb für diese Einrichtungen;

Fig. 3

eine Aufsicht auf die Baugruppe nach Fig. 2, gesehen aus Blickrichtung III, in einer Stellung "Minimaler Niederhaltedruck";

Fig. 4

die Ansicht nach Fig. 3, wobei ein Abschnitt einer Grundplatte eines Kurvenhebels des Antriebs weggelassen ist;

Fig. 5

in einer zu Fig. 3 ähnlichen Darstellung die Baugruppe in einer Position "Maximale Fußlüftung";

Fig. 6

die Baugruppe nach Fig. 5, wiederum mit abschnittsweise weggelassener Grundplatte des Kurvenhebels;

Fig. 7

in einer zu Fig. 3 ähnlichen Darstellung die Baugruppe in einer Position "Mittlere Fußlüftungshöhe";

Fig. 8

die Baugruppe nach Fig. 7, wiederum mit abschnittsweise weggelassener Grundplatte des Kurvenhebels;

Fig. 9

in einer zu Fig. 3 ähnlichen Darstellung die Baugruppe in einer Position "Maximaler Niederhaltedruck";

Fig. 10

die Baugruppe nach Fig. 9, wiederum mit abschnittsweise weggelassener Grundplatte des Kurvenhebels;

Fig. 11

in einer zu Fig. 2 ähnlichen Darstellung eine weitere Ausführung einer Baugruppe mit einer Andruck-Einstelleinrichtung zur Vorgabe eines Niederhaltedrucks, den ein Nähfuß beim Niederhalten auf Nähgut ausübt, mit einer Lüftereinrichtung zum Lüften des Nähfußes und mit einem gemeinsamen Antrieb für diese Einrichtungen, wobei die Baugruppe nach Fig. 11 anstelle der Baugruppe nach Fig. 2 zum Einsatz kommen kann;

Fig. 12

eine Aufsicht auf die Baugruppe nach Fig. 11, gesehen aus Blickrichtung XII, in einer Stellung "Minimaler Niederhaltedruck", wobei ähnlich wie in der Fig. 4 ein Abschnitt einer Grundplatte eines Kurvenhebels des Antriebs weggelassen ist;

Fig. 13

in einer zu Fig. 12 ähnlichen Darstellung die Baugruppe in einer Position "Maximale Fußlüftung";

Fig. 14

in einer zu Fig. 12 ähnlichen Ansicht die Baugruppe in der Position "Mittlere Fußlüftungshöhe";

Fig. 15

in einer zu Fig. 12 ähnlichen Ansicht die Baugruppe in der Position "Maximaler Niederhaltedruck";

Fig. 16

perspektivisch eine Kurvenscheibe der Baugruppe nach Fig. 11; und

Fig. 17

perspektivisch den Kurvenhebel der Baugruppe nach Fig. 11.

An embodiment of the invention is explained below with reference to the drawing. In this show:

Fig. 1

perspective a sewing machine in a front view;

Fig. 2

also a perspective of an assembly of the sewing machine Fig. 1 with a pressure setting device for specifying a hold-down pressure which a presser foot exerts on the material when holding it down, with a fan device for lifting the presser foot and with a common drive for these devices;

Fig. 3

supervision of the assembly Fig. 2 , seen from viewing direction III, in a position "minimum hold-down pressure";

Fig. 4

the view after Fig. 3 , wherein a portion of a base plate of a cam lever of the drive is omitted;

Fig. 5

in one too Fig. 3 similar representation the assembly in a position "maximum foot ventilation";

Fig. 6

the assembly after Fig. 5 , again with the base plate of the cam lever omitted in sections;

Fig. 7

in one too Fig. 3 similar representation the assembly in a position "medium foot ventilation height";

Fig. 8

the assembly after Fig. 7 , again with the base plate of the cam lever omitted in sections;

Fig. 9

in one too Fig. 3 similar representation the assembly in a position "maximum hold-down pressure";

Fig. 10

the assembly after Fig. 9 , again with the base plate of the cam lever omitted in sections;

Fig. 11

in one too Fig. 2 Similar representation another embodiment of an assembly with a pressure setting device for specifying a hold-down pressure that a presser foot exerts on the material when holding it down, with a fan device for lifting the presser foot and with a common drive for these devices, the assembly according to Fig. 11 instead of the assembly Fig. 2 can be used;

Fig. 12

supervision of the assembly Fig. 11 , seen from viewing direction XII, in a position "minimum hold-down pressure", similar to that in the Fig. 4 a portion of a base plate of a cam lever of the drive is omitted;

Fig. 13

in one too Fig. 12 similar representation the assembly in a position "maximum foot ventilation";

Fig. 14

in one too Fig. 12 similar view the assembly in the position "medium foot ventilation height";

Fig. 15

in one too Fig. 12 similar view the assembly in the position "maximum hold-down pressure";

Fig. 16

in perspective a cam of the assembly Fig. 11 ; and

Fig. 17

perspective the cam lever of the assembly Fig. 11 .

A sewing machine 1 has a stand 2, an arm 3 and a head 4, so that together with a housing base plate 5 there is an overall C-shaped construction of the sewing machine 1. An arm shaft driven via a main drive (not shown in detail) drives a needle bar 6 with a sewing needle 7 fixed thereon up and down. The needle 7 passes through a stitch hole in a stitch plate, which forms part of a support plate 8, which in turn represents the top of the housing base plate 5 of the sewing machine 1.

The sewing machine 1 has a presser foot 9, which is also referred to as a presser foot, for holding down sewing material during sewing. The presser foot 9 is mounted on a presser foot bar 10.

To set a hold-down pressure that the presser foot 9 exerts on the material to be held down and to release the presser foot, an assembly is used in the Fig. 2 is generally designated with the reference number 11.

The assembly 11 includes a pressure adjusting device for specifying the hold-down pressure, a fan device for lifting the presser foot and a common drive for these two devices. The pressure setting device and the fan device are explained in detail below. The common drive is designed as a stepper motor 12. A drive shaft 12a (see e.g. Fig. 3 ) of the stepping motor 12 is oriented away from the presser foot rod 10, so that a free end of the drive shaft 12a, that is in the opposite direction to the viewing direction III of the view of FIG Fig. 3 pointing to the viewer.

The drive shaft of the stepper motor 12 is rotatably connected to a cam 13. The cam disc 13 interacts with a cam lever 14 on the one hand to lift the presser foot 9 and on the other hand to drive the pressure setting device. The cam lever 14 interacts with the cam plate 13 over an overall pivoting path of the cam plate 13. The cam lever 14 is in turn non-rotatably connected to a fan shaft 15 which runs parallel to the arm shaft in the arm 3 of the sewing machine 1 and is rotatably mounted on a frame of the sewing machine 1. A fan lever 16, which cooperates with a presser foot driver 17, which is fixedly connected to the presser foot rod 10, is connected in a rotationally fixed manner to the fan shaft 15. The fan shaft 15 serves to transmit a changeover force from the cam lever 14 to the presser foot 9.

At the end opposite the cam lever 14, the fan shaft 15 is connected in an articulated manner to a longitudinal axis of the fan shaft with a pull rod 18, which is used to press the in the Fig. 2 presser foot 9, not shown, presses from above via a sleeve 19 against the compression spring 21.

Between another, frame-fixed sleeve 20, which is penetrated by the presser foot rod 10, and the presser foot driver 17 is one Compression spring 21 is arranged, which partially surrounds the presser foot rod 10 in a helical shape.

The 2 to 4 show the assembly 11 in the drive position "minimum hold-down pressure". In comparison to Fig. 3 is in the Fig. 4 a portion of a base plate of the cam lever 14 is omitted to further illustrate its interaction with the cam lever 14.

A first scanning pin 22 of the cam lever 14, which represents a first scanning body of the cam lever 14, is inserted into a cam recess 23 of the cam disk 13, which defines the cam lever position "minimum hold-down pressure". In the assigned pivot position of the fan shaft 15, the pull rod 18 exerts a minimal compressive force on the sleeve 19. The compression spring 21 is minimally biased. The force of the compression spring 21 is transmitted to the presser foot rod 10 via the presser foot driver 17, so that a corresponding, minimal hold-down pressure of the presser foot 9 results when the sewing machine 1 is in operation. In this "minimum hold-down pressure" drive position, the fan lever 16 is out of engagement with the presser foot driver 17.

The 5 and 6 show the drive position "Maximum foot ventilation". To reach this position, proceed from the "Minimum hold-down pressure" position 2 to 4 the stepper motor 12 operated so that its drive shaft by about 80 ° counterclockwise from the perspective of 3 to 6 is twisted. As a result, a second scanning pin 24 of the cam lever 14, which represents a second scanning body of the cam lever 14, has run clockwise on the cam 13 to a cam area 25 in which the cam 13 in turn acts as a lever on the second scanning pin 24. In this position, the fan lever 16 presses the Presser foot driver 17 against the compressive force of the compression spring 21 in the direction of the frame-fixed sleeve 20 upwards and takes the presser foot rod 10 for lifting the presser foot 9.

The two scanning pins 22, 24 of the cam lever 14 are arranged separately from one another. The two scanning bolts 22, 24 are firmly connected to the cam lever 14.

The two scanning bolts 22, 24 are arranged such that they interact with the cam plate 13 in each case at least in a section of the total pivoting path of the cam plate 13. In the swivel path area of the cam lever position "minimum hold-down pressure" (cf. the 3 and 4 ) the first scanning pin 22 interacts with the cam plate 13 in the region of the curve recess 23. In the further cam lever position "Maximum foot ventilation" (cf. the 5 and 6 ) the second scanning pin 24 interacts with the cam area 25.

The curve recess 23 on the one hand and the curve area 25 on the other hand represent two concave curve sections of the cam disk 13. Between these two concave curve sections 23, 25, the cam disk 13 has a convex curve section 26 which is designed in the form of a nose of the curve line of the cam disk 13.

The 7 and 8 show the drive position "medium foot ventilation height" between the two drive positions described above "minimum hold-down pressure" and "maximum foot ventilation". In this drive position "average foot ventilation height", the convex cam section 26 engages between the two scanning bolts 22, 24 and thus secures the contact of the cam lever 14 on the cam disc via a positive locking contribution 13. Regardless of a force that is transmitted to the cam lever 14, for example, via the sewing material, the presser foot 9 and the presser foot rod 10, its contact position on the cam disk 13 remains secured.

In a section of the area between the drive position "minimum hold-down pressure" (cf. for example the 3 and 4 ) and the drive position "Maximum foot ventilation" (cf. 5 and 6 ) the two scanning pins 22, 24 act together with the cam disc 13, that is to say they are in contact with the cam disc 13 at the same time.

9 and 10 show the drive position "maximum hold-down pressure". In comparison to Fig. 3 the stepper motor 12 is converted so that its drive shaft follows the cam disk 13 in comparison to the position Fig. 3 has pivoted about 320 ° clockwise. The first scanning pin 22 of the cam lever 14 runs on the cam 13 up to a cam area 27 "maximum hold-down pressure". In this "maximum hold-down pressure" position, the second sensing pin 24 is out of engagement with the cam disk 13.

In this position, the pull rod 18 is shifted downward due to its eccentric connection to the fan shaft 15 and accordingly exerts a pulling force on the sleeve 19, which is pressed downward by the pull rod 18 at a maximum. As a result, the compression spring 21 is biased to a maximum. The result is the maximum hold-down pressure which the presser foot rod 10 and thus the presser foot 9 exerts on the material to be sewn during operation of the sewing machine 1. In the "maximum hold-down pressure" position, the fan lever 16 is again out of engagement with the presser foot driver 17. As a result, the cam lever 14 is compared to the drive position "Minimum hold-down pressure" after Fig. 3 in the drive position "Maximum hold-down pressure" after the 9 and 10 pivoted about 60 ° counterclockwise.

The cam disk 13 and the cam lever 14 thus cooperate in such a way that the sewing foot 9 is released in one direction of rotation of the cam disk and the pressure setting device is driven in an opposite direction of rotation.

An adjustment range of the drive shaft of the stepper motor 12 between the cam lever position "minimum hold-down pressure" (cf. Fig. 3 ) and the cam lever position "maximum hold-down pressure" (cf. Fig. 9 ) is more than 180 °.

The stepper motor 12 can be operated by an operator for foot lifting, for example, via a pedal of the sewing machine 1.

In order to specify the hold-down pressure, a presetting can be made via a control device 26, which in the Fig. 1 is shown schematically. The control device 26 is in signal connection with the stepper motor 12 in a manner not shown in detail.

Based on 11 to 15 A further embodiment of an assembly 28 for specifying a hold-down pressure and for releasing a presser foot is explained below, which can be used in the sewing machine 1 instead of the assembly 11 explained above. Components and functions which correspond to those which have already been explained above with reference to the assembly 11 have the same reference numerals and will not be discussed again in detail.

In the assembly 28, the stepper motor 12 is arranged such that its drive shaft in the direction of the presser foot rod 10, that is again in the opposite direction to the viewpoint XII of the viewer of the Fig. 12 to, is oriented. The orientation of the drive shaft of the stepping motor 12 in relation to the push rod 10 is therefore opposite to the assembly 11 in the assembly 28.

The Fig. 11 and 12th show the drive position "minimum hold-down pressure". Here again the first scanning pin 22 of the cam lever 14 comes into contact with the cam disk 13 in the cam recess 23.

The Fig. 13 shows the drive position "Maximum foot ventilation". The stepper motor 12 of the assembly 28 is operated in such a way that the cam disk 13, which is firmly connected to the drive shaft thereof, is rotated counterclockwise by approximately 180 ° from the perspective of FIG 12 and 13 , based on the drive position "minimum hold-down pressure" Fig. 12 , is twisted. In this drive position "maximum foot ventilation", the second scanning pin 24 plunges into a further concave curve area 25 of the cam plate 13, which corresponds to the curve area 25 of the assembly 11. This pivoting of the cam disc 13 causes the cam lever 14 to be pivoted counterclockwise by approximately 45 °, starting from the "minimum foot pressure" drive position. In this position, the fan lever 16 in turn presses the presser foot driver 17 against the pressure force of the compression spring 21 in the direction of the frame-fixed sleeve 20, as described above in connection with FIGS 5 and 6 to assembly 11 already explained.

The Fig. 14 shows the drive position "middle foot ventilation", ie an intermediate drive position between the positions "minimum foot pressure" Fig. 12 and "Maximum foot ventilation" Fig. 13 . In this drive position "average foot lifting height", the two drive bolts 22, 24 act simultaneously with the convex curve section 26 of the cam disk 13.

Between the two concave curve areas 23 and 25 of the cam disk 13 of the assembly 28 there is in turn a convex curve section 26 which is more voluminously shaped in the cam disk 13 of the assembly 28 than in the cam disk 13 of the assembly 11.

Fig. 15 again shows the drive position "maximum hold-down pressure". Compared to the drive position after Fig. 12 the cam disk 13 of the assembly 28 is pivoted clockwise by approximately 210 °, which in turn takes place via the stepper motor 12. The first scanning pin 22 runs on the cam disk 13 of the assembly 28 up to the cam area 27 "maximum hold-down pressure". The cam lever 14 is in this drive position "maximum hold-down pressure" compared to the drive position "minimum foot pressure" in the view according to the Fig. 12 and 15 pivoted about 90 ° clockwise.

In this position, the pull rod 18 is displaced downward due to its eccentric connection with the fan shaft 15 and accordingly exerts a pulling force on the sleeve 19, which is pressed downward accordingly by the pull rod 18 at a maximum. As a result, the compression spring 21 is biased to a maximum. The result is the maximum hold-down pressure which the presser foot rod 10 and thus the presser foot 9 exerts on the material to be sewn during operation of the sewing machine 1. In the position "maximum hold-down pressure" the fan lever 16 is again out of engagement with the presser foot driver 17. In this “maximum hold-down pressure” position, the second sensing pin 24 is out of engagement with the cam disk 13.

In the "maximum hold-down pressure" position, the cam area 27 also serves as a stop for referencing the stepper motor 12. For this purpose, the stepper motor 12 moves into the "maximum hold-down pressure" drive position until the first scanning pin 22 abuts the stop formed by the cam area 27. The curve region 27 designed as a stop does not require the use of further referencing sensors, which can otherwise be formed by a light barrier or an inductive switch.

In the assembly 11, for example, "minimum hold-down pressure" (cf. 3 to 4 ) the two scanning pins 22 and 24 in the supervision according to the 3 and 4 seen between the fan shaft 15 and the drive shaft 12a of the stepping motor 12. In assembly 28, for example, "maximum foot ventilation" is in the drive position (cf. Fig. 13 ) the two tracing pins 22, 24, as seen from above Fig. 13 , approximately at the level of the drive shaft 12a of the stepping motor 12.

The 16 and 17 show the cam 13 in perspective ( Fig. 16 ) and the cam lever ( Fig. 17 ) of assembly 28.

The cam disc 13 and the cam lever 14 of the assembly 28 can be used as a retrofitting assembly for retrofitting an existing drive assembly, the fan lever of this existing drive assembly originally having exactly one scanning pin.

Claims (9)

1. Sewing machine (1)

   - with at least one sewing foot (9) for holding down a piece of fabric during sewing,

   - with a pressure adjusting device for setting a hold-down pressure, exerted by the sewing foot (9) when holding down the piece of fabric,

   - with a lifting device for lifting the sewing foot,

   - with a common drive (12) for the pressure adjusting device and for the lifting device,

   - wherein a cam disc (13), which interacts with a cam lever (14), on the one hand, to lift the sewing foot (9) and, on the other hand, to drive the pressure adjusting device, is non-rotatably arranged on a drive shaft of the common drive (12), wherein the cam lever (14) is configured in such a way as to interact with the cam disc (13) along a total pivoting path of the cam disc (13),
   characterized in that

   - the cam lever (14) has two cam followers (22, 24) arranged separately from one another, the cam followers (22, 24) being arranged so as to interact with the cam disc (13) in each case at least in a section of the total pivoting path of the cam disc (13).
2. Sewing machine as claimed in claim 1, characterized in that the two cam followers (22, 24) are arranged so as to simultaneously interact with the cam disc (13) at least in a section of the total pivoting path of the cam disc (13).
3. Sewing machine as claimed in claim 2, characterized in that a cam of the cam disc (13) has a convex cam section (26) adjoined by a respective concave cam section (23, 25) on either side of the convex cam section (26), wherein the convex cam section (26) is the one via which a simultaneous interaction of the two cam followers (22, 24) with the cam disc (13) takes place.
4. Sewing machine as claimed in any one of claims 1 to 3, characterized in that the two cam followers (22, 24) are configured as followers, which are rigidly connected to the cam lever (14).
5. Sewing machine as claimed in any one of claims 1 to 4, characterized in that the cam disc (13) and the cam lever (14) interact in such a way that a lifting of the sewing foot (9) takes place in one rotational direction of a rotation of the cam while a driving of the pressure adjusting device takes place in a rotational direction counter thereto.
6. Sewing machine as claimed in any one of claims 1 to 5, characterized in that the cam disc (13) has a cam recess (23) configuring a concave cam section of the cam disc (13) for setting a "minimum hold-down pressure" cam lever position.
7. Sewing machine as claimed in any one of claims 1 to 6, characterized by a lifting shaft (15) for the transmission of a switch operation force from the cam lever (14) to the sewing foot (9).
8. Sewing machine as claimed in any one of claims 1 to 7, characterized in that the drive (12) is configured as a stepper motor (12).
9. Sewing machine as claimed in any one of claims 1 to 8, characterized by an adjusting range of the drive shaft of the common drive (12) between a "minimum hold-down pressure" cam lever position and a "maximum hold-down pressure" cam lever position of more than 180°.

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