EP0378965B1 - Presser attachment device for a sewing machine - Google Patents

Description

The present invention relates to presser devices for sewing & machine, comprising, on the one hand, a rocking lever, one end of which carries a presser foot and, on the other hand, a control mechanism for driving this lever. a first limit angular position, in which the foot is applied to the material to be sewn, in a second limit angular position, in which this foot is distant from said material, said mechanism comprising at least one guide ramp and at least one rolling member capable of moving in contact with said ramp, the second end of said lever being kinematically integral with said rolling member.

Such a device is described in US Pat. No. 4,480,566 in which the mechanism for controlling the tilting of the lever carrying the presser foot is actuated by the needle bar of the machine, a bar of which it is kinematically integral, this foot thus being driven in a position distant from the material to be sewn when the machine needle is engaged in the material to ensure the formation of the stitch in cooperation with the rotary hook of the machine so that the material to be sewn can, moreover, be entrained laterally by the needle bar throughout the throwing movement thereof. The presser foot is, on the contrary, driven and maintained in the position applied to the material to be sewn as long as the needle bar occupies an axial position in which the needle is distant from the material: the presser foot then exerts pressure on the material to be sewn. sufficient to press it on the feed dogs of this material and thus ensure the axial displacement of the latter between two successive dives of the sewing needle. The sewing machine including this type of presser device is particularly well suited to sewing decorative patterns of relatively large size, both in length and in width.

The invention aims to produce a fabric press device having a basic structure encompassing characteristics similar to those of the device which is the subject of US patent 4,480,566 in a combination allowing its use in a sewing machine of traditional architecture such that the stuffing press remains constantly supported on the material sewing, that is to say whatever the axial position occupied by the needle bar, whether or not the needle is stitched in the fabric.

In particular, the stuffing device according to the invention is characterized, from that described by this American patent, by the fact that the control mechanism further comprises at least one jack, exerting a thrust on said tensioning rolling member keeping this member in contact with said ramp, and means making it possible to move the point of application of the jack on the rolling member of a first portion of this member on a second portion thereof and vice versa, said portions of the rolling member being located, for the first, between the zone of mutual contact between this member and the ramp, said lever then occupying said first limit tilting position, and, for the second, opposite from said first end of the lever with respect to said zone of mutual contact, the position occupied by said lever corresponding to said second angular limit position thereof.

The new proposed structure allows, on the one hand, the realization of a control mechanism for the lifting of the stuffing cloth Likely to be actuated easily, on request of the user, for example by a simple stepping motor controlled by a microprocessor, in the case of a computerized sewing machine, on the other hand, an automatic lifting of the stuffing press to the desired height when sewing materials of various thicknesses or having local extra thicknesses, even important, without these extra thicknesses causing a blockage of the material preventing its axial drive between two successive dives of the sewing needle for example.

• La figure 1 en est une vue en élévation latérale, avec coupe partielle de certains éléments;
• La fig. 2 est une vue de face;
• La fig. 3 est une vue en plan et en coupe partielle selon III-III de la fig. 1.
• La fig. 4 est une vue partielle, de face, selon une première variante d'exécution;
• La fig. 5 est une vue en coupe partielle selon V-V de la fig. 4;
• La fig. 6 est une vue selon VI-VI de cette fig. 4;
• La fig. 7 est une vue de détail, avec coupe partielle, d'une seconde variante d'exécution;
• La fig. 8 montre le schéma d'un circuit électrique de commande d'un dispositif presse-étoffe selon l'invention.

The accompanying drawings represent, by way of example, an embodiment of the present invention:

• Figure 1 is a side elevational view, with partial section of certain elements;
• Fig. 2 is a front view;
• Fig. 3 is a plan view and in partial section along III-III of FIG. 1.
• Fig. 4 is a partial front view, according to a first alternative embodiment;
• Fig. 5 is a partial sectional view along VV of FIG. 4;
• Fig. 6 is a view along VI-VI of this FIG. 4;
• Fig. 7 is a detail view, with partial section, of a second alternative embodiment;
• Fig. 8 shows the diagram of an electrical circuit for controlling a stuffing device according to the invention.

In the drawing (fig. 1), l is the base of the housing of a machine to be sewn on which stands a column 2 carrying two arms 3 and 4 of which the first, 3, contains in particular a loop sensor and its control mechanism as well as a device for driving the material to be sewn, all not visible, and whose second arm, 4, carries a mechanism, not shown, for controlling the sliding, alternately in two opposite directions, of a needle bar 5, as well as a device 6 for driving this bar 5 in its throwing movement and a stuffing device 7 whose features will be described below.

The central motor of the sewing machine, not shown, on which depend in particular the drive of the loop sensor, that of the material to be sewn and that of the bidirectional vertical movement of the needle bar, is arranged in column 2, alongside d 'a step-down transformer and a retressor assembly, all not visible in the drawing, for the current supply of the motor as well as an electronic circuit, not shown, grouping in the form of "solid state" chips, memories storage of programmed information for controlling the various functions of the sewing machine, and one or more microprocessors on which this control depends. All of these means, their coupling and functions are well known to those skilled in the art and will not be described here.

On the housing, and more particularly on its right front face in the drawing, the sewing machine shown carries a control keyboard of which only a switch 8, for actuating the stuffing device 7, has been shown in FIG. 1.

The device 6 is of the type described in document EP A1 0377404 to which reference will be made for the structural details.

However, let us say that it comprises a stepping motor 9, with a vertical axis, for controlling the tilting of a lever 10, articulated at 11 on a fixed support 12 and having a frustoconical opening forming a seat for the external face, with a spherical profile, of a bearing 13, placed in line with a second bearing 14, of structure identical to that of the bearing 13 and engaged in a corresponding seat formed in the upper flange 9a of the motor 9.

The bearings 13 and 14 are held in their respective seats by a spring 15, stretched between these bearings and crossed, like the bearings themselves, by the needle bar 5, the latter being moreover mounted to slide in these bearings.

Under the support 12 is fixed a lamp 16 ensuring the lighting of the sewing area of the arm 3 through a window 4a formed in the wall of the arm 4. A second window 4b, of oblong shape, ensures the passage of the needle bar 5 and allows its throwing movements.

The presser device 7 comprises (fig. 1) a lever 70 at the right end of which is articulated, by an axis 70a, a presser foot 71 located below the needle bar 5 and that the lever 70 is intended to drive either in a low position, shown in solid lines, in which the foot presses the material to be sewn onto a needle plate 3a which has the upper face of the arm 3 of the machine (fig. 3) and more precisely on the claw , not shown, for driving the sewing material, from right to left in the drawing or vice-versa, either in a high position, shown in phantom, which is vertical to that occupied by the foot 71, in the low position .

In this high position, the material to be sewn can be moved freely by hand, in particular to position the part to receive the seam under the needle 5a carried by the needle bar 5.

At this point, it should be noted that the stuffing device according to the invention allows the execution of seams in a very thick fabric, even becoming suddenly irregular, without blocking of this fabric by the foot 71.

Indeed, in this device, the lever 70 can easily switch in one or the other of two directions F₁ and F₂ even when the foot 71 is applied to the fabric to be sewn, which explains the ease with which the machine sewing machine shown can sew stacks of fabric even of substantial thickness.

To do this, the lever 70 carries, on its left part (fig. 1), a flat and rectangular sole, 70b, projecting on each side of the lever and having, along its two longitudinal edges, two toothed sectors 70c and 70d each resting on a straight track specific to each sector, 72a, respectively 72b (figs 1 and 2) with toothed profile, cut on the upper face of a console 72 secured to the frame, partially shown of the sewing machine.

As can be seen in the drawing, the pitch and the shape of the toothing of the toothed sectors 70c and 70d and those of the rolling tracks 72a and 72b are identical, the toothing of the former perfectly meshing with that of the latter.

On the other hand, if the toothing of the tracks 72a and 72b extends horizontally, that of the sectors 70c and 70d of the lever 70, develops in an arcuate profile such that, as the lever 70 swings in the direction F2, the sectors 70c and 70d roll literally on the tracks 72a and 72b, to the left in the drawing, over a length compensating, at all times, for the movement to the right that the foot 71 would not fail to effect if the lever 70 was simply articulated around a fixed axis.

Similar compensation, but in the opposite direction, of course takes place when the lever 70 is driven from its position shown in phantom in that in solid line.

This cinematism is made necessary by the fact that the foot 71 must be able to be raised even if the needle 5a is in its lowest position and this without encountering this needle.

In an alternative embodiment, not shown, it would of course be possible to have rectilinear toothing for the sectors 70c and 70d, the rolling tracks 72a and 72d having a curvature suitable for the desired purpose.

According to another variant, also not shown, one could also design sectors 70c and 70d as well as raceways 72a and 72b each having their own arcuate profile, traced so as to allow the same type of operation to be obtained as in the case of the assembly of fig. 1.

Finally, it is understood that both these sectors and these tracks could have no teeth and have a practically smooth profile, it being understood, however, that it would then be necessary to make a choice of materials offering good mutual adhesion.

The actuation of the lever 10 can be obtained either by means of a motorized control, such as that shown in Figures 1 and 8 in particular, or even by manual control, of the type visible in Figs 4 and 6 for example. It is, of course, possible to provide only the second of these possibilities, in particular in the case of low-end sewing machines, or, on the contrary, that the first, for sewing machines with high performance, such in particular electronic microprocessor sewing machines. Alternatively, such a type of machine could include both motorized control and manual control of the stuffing device according to the invention.

In the case of a motorized control, this device comprises a stepping motor 73 whose windings E₁ and E₂ (fig. 8) are supplied, in an appropriate manner, by "drivers" D₁ and D₂ controlled by a microprocessor µP, which, in a computerized sewing machine, can also be used for general control of the machine's functions. The actuation of the switch 8 causes the impulse type information to be sent to the microprocessor alternately determining the commissioning of the driver D₁ or of the driver D₂ for a period of time sufficient to drive the foot 71 from its low position in its high position, and vice versa.

The housing of the motor 73 carries a barrel 73a, articulated on the housing of the sewing machine by means of two axes 73b (figs 1 and 3) projecting from the barrel 73a, on either side thereof. . This barrel is crossed by the left end, in the drawing, of a threaded rod 73c extending in the extension of the shaft, not shown, of the motor, integral with this shaft, and engaged in a threaded passage 74a that has an axis 74c carrying two rollers 74b and forming part of a carriage 74 capable of rolling on the soleplate 70b of the lever 70, from the right end thereof to its left end and vice versa, according to the direction of rotation of the threaded rod 73c, that is to say of the armature of the stepping motor. The length of the carriage stroke on the sole 70b is fixed by the number of control pulses sent by the drivers D₁ and D₂ on the windings E₁ and E₂ each time the switch 8 is actuated. This number will obviously be identical for each driver so that the stroke of the carriage will be the same in one direction or the other of its movement on the sole 70b.

As seen in the drawing, the carriage 74 is fixed to the lower end of a bar 75 whose upper end, forked at 75a, slidably embraces a guide rod 76 fixed horizontally to the housing of the machine.

Around the bar 75 is arranged a spring 77, prestressed between the rod 76 and the carriage 74 on which it is supported and whose length is such that it remains under tension even when the bar 75 which carries it is disposed in its position inclined, shown in phantom in the drawing.

The assembly formed by the bar 75, the rod 76 and the spring 77 forms a sort of thrust cylinder exerting its action on the sole 70b of the lever 70 of which it will determine the angular position according to the position occupied at all times by the carriage 74 on the sole 70b. It will be recalled that the latter can be moved on this sole by rotation of the threaded rod 73c in one direction to the other, in the direction desired for the movement of the carriage 74.

Indeed, as the lever 70 is free to switch in the direction F₁ or F₂, by rolling its toothed sectors 70c and 70d on the corresponding tracks 72a and 72b, it will suffice that the vertical component of the force exerted by the spring 77 on the carriage 74 passes to the left, in the drawing (fig. 1), of the support zone of the sectors 70c and 70d on these tracks so that the lever 70 switches in the direction F₂, from its low position to its high position.

The lever 70 will resume its low position as soon as, by a movement in the opposite direction of the carriage 74, the same vertical component of the force exerted by the spring 77 will pass to the right the support area of this lever.

In the low, working position, of the foot 71, this exerts maximum pressure on the fabric which it is responsible for applying against the claws, not shown, of the mechanism for driving this fabric: in fact, c 'is in this position of the foot 71 that the spring 77 develops its maximum force because, the bar 75 occupying a vertical position, the deflection of this spring is then maximum.

If, during sewing, the thickness of the portion of the material to be sewn arriving at a given instant under the presser foot is much greater than that of the rest of this material, the foot 71 and the lever 70 will be lifted quantity corresponding to this thickness: at the limit, the lever 70 and its foot 71 may even be temporarily driven into the high position shown in phantom in the drawing, giving way to the excess thickness of the material to be sewn without there being machine blocked.

In fact, in such a case, the bar 75 will rise vertically by sliding its forked end 75a on the rod 76 and compressing the spring 77.

This bar will return to its usual axial position, smoothly, by relaxation of the spring 77, as soon as the foot 71 has passed over the temporary excess thickness of the material to be sewn.

Thus, the foot 71 and the lever 70 are somehow mounted on a real suspension allowing them to easily absorb all the obstacles that may present to them the surface of a sewing piece, even of relatively high thickness as is for example the case when it is a question of assembling several layers of coarse Jean type canvas or corduroy for example.

As already described, the stuffing device according to the invention may also include only a manual control of the kind illustrated by way of example in FIGS. 4 to 6.

Such a device differs from that described with reference to FIGS. 1 to 3 and 8 by the fact that the motor 73 and its annexed parts as well as the circuit which is the subject of FIG. 8 are deleted, with the corresponding modifications for the sewing machine housing especially. Therefore, the drive of the carriage 74 on the sole 70b * of the lever 70 * will be carried out by corresponding horizontal displacement, carried out manually, of a pull tab 78 secured to the carriage 70 * b and passing through a slot f formed in the housing of the machine, zipper that the user can control by finger action on a button 78 * fixed to the free end thereof (figs 1 and 6).

The stroke of the carriage 74 on the sole 70 * b of the lever 70 * is limited by meeting the rollers 74 * b with two pairs of stops, 70 * d and 70 * e alternately depending on the direction of movement of this carriage (fig. 5 ).

In a particularly advantageous embodiment (fig. 7), the rolling tracks 172 intended for the toothed sectors 170c of the lever 170 carrying the foot 171 could be cut from a single piece 180 constituting at the same time the lower flange of a motor step by step 190 for controlling the throwing movement of the needle bar of the machine. The upper flange of this motor, 180 *, would include a fork 180 * a at the end of which would be fixed the rod 176 allowing the axial sliding of the bar 175 of the pressure cylinder formed by this bar in cooperation with a coil spring 177.

The solution mentioned above makes it possible to combine the stuffing device according to the invention, the device for controlling the throwing of the needle bar and this needle bar to form a single aggregate, capable of being manufactured and mounted of independently, independently of the rest of the sewing machine, even in a workshop or factory distant from the final assembly location and at a time different from that of this assembly.

It also makes it possible to facilitate after-sales service, in particular in all cases where any repairs must be carried out in places very distant from the place of production of the machine, and requiring only simple tools. as well as unskilled personnel.

The invention is, of course, not limited to what has been described or shown: in particular, it is obvious that the spring jack visible in particular in FIG. 1 could, for example, be replaced by a hydraulic or pneumatic cylinder.

In addition, in order to obtain an adaptation of the pressure exerted by the device described on the material to be sewn as a function of the nature of this material, it would be possible, in an alternative embodiment of the control circuit illustrated in FIG. . 8, to ensure that the windings E₁ or E₂ receive only a driving impulse by action exerted on the switch 8.

In this way, it will be possible to drive the jack in any intermediate position included, on the one hand, between the right end, in the drawing, of the sole 70b, respectively 170b (FIGS. 1 and 7), and, on the other hand, the bearing zone of sectors 70c and 70d, respectively 170c, on the rolling tracks 72a and 72b, respectively 172, and thus vary the importance of the vertical component of the force developed by this jack on the sole and, therefore , on the presser foot.

One could, moreover, obtain a substantial modulation of the above effect by giving the surface of the sole 70b, respectively 170b (figs 1 and 7), a profile different from the planar profile envisaged in the embodiments shown, so to punctually vary the state of compression of the spring of the jack as a function of the position occupied at all times by the carriage 74 on this sole.

According to another variant, also not shown, the adaptation mentioned above could be automatic thanks to a computerized program operated by the microprocessor of the circuit (figg. 8) and which would be accessible from various command keys, corresponding, each at a different position of the jack on the sole 70b, respectively 170b (figs 1 and 7), that is to say at an optimal pressure exerted by the presser foot of the machine on the material to be sewn, according to the characteristics which their own and the nature of the sewing pattern.

Claims (13)

1. A material presser device for a sewing machine, comprising a tilting lever (70) whose first end carries a presser foot (71) and also comprising an actuating mechanism to bring the said lever into a first angular end position, in which position the foot (71) is applied to the material to be sewn, and into a second angular end position, in which the foot is at a distance from the material, the mechanism comprising at least one guide ramp (72a, 72b) and at least one rolling member (70c, 70d) displaceable upon contact with the ramp, the second end of the lever (70) being rigid with the rolling member for displacement therewith, characterised in that the actuating mechanism also comprises at least one jack (7) exercising a thrust on the rolling member (70c, 70d) tending to maintain the member in contact with the ramp (72a, 72b) and means allowing the application point of the jack to be displaced on the rolling member from a first portion of the said member to a second portion thereof and vice-versa, the first portion of the member being situated between the mutual contact region of the member and the ramp, the lever occupying its said first tilted end position, and the second portion of the member being situated opposite the first end of the lever with respect to the mutual contact region, the position occupied by the lever corresponding to its second angular end position.
2. A device according to claim 1, characterised in that the ramp (72a, 72b) and/or the rolling member (70c, 70d) have a mutual contact surface of a profile such that when the member is displaced on the ramp, the member drives the lever (70) in accordance with both an angular and a translatory movement, the combination of the two movements resulting in a vertical displacement of the first end of the lever (70) and of the presser foot (71).
3. A device according to claim 1, characterised in that the mutual contact surface of the rolling member (70c, 70d) and that of the guide ramp (72a, 72b) are toothed, the rolling member and the ramp mutually meshing by their respective toothing.
4. A device according to claim 3, characterised in that the said mechanism comprises a first (70c) and a second (70d) rolling member arranged at different sides of the lever (70) and also a first (72a) and second (72b) guide ramp, the first rolling member and the second rolling member respectively meshing with the first guide ramp and second guide ramp.
5. A device according to claim 4, characterised by an intermediary sole plate (70b) forming a body with the first and second rolling members (70c, 70d), the jack (7) being supported on the sole plate by its thrust end, and the said means allowing the point of application of the jack on the sole plate to be moved from a first area thereof, wherein the lever (70) occupies its first angular end position, to a second area of the ramp, and vice-versa, the angular position of the lever then corresponding to its said second angular end position.
6. A device according to claim 5, characterised in that the jack is hydraulically or pneumatically operated.
7. A device according to claim 5, characterised in that the jack is one in which energy is resiliently stored.
8. A device according to claim 7, characterised in that the jack (7) comprises a rigid elongate member (75), one end of which rests on the support plate (70b) and the second end of which is pivoted with respect to a fixed point (76), and it also comprises a helical spring (77) enclosing the said member (75) and compressed between the first end of the member and the said fixed pin (76) in such a manner that the spring exerts a thrust on the sole plate (70b) regardless of the portion on which the jack rests.
9. A device according to claim 8, characterised in that it includes means (73, 73c, 74) controlling the tilting of the rigid member about the fixed point (76) (fig. 1).
10. A device according to claim 9, characterised in that the end of the jack resting on the sole plate (70b) has a carriage (74) rolling on the sole plate (70b).
11. A device according to claim 10, characterised in that the device includes a rod (78) displaceably rigid with the carriage (74), with at least one part thereof being accessible to the user to allow control of the movement of the thrust end of the jack to different points along the length of the sole plate of the lever.
12. A device according to claim 10, characterised in that the carriage (74) has a nut (74a, 74c) whose axis is orientated parallel to the required path for the carriage on the sole plate (70b) and it comprises a stepper motor (73), whose motor shaft (73a) controls the rotation of a threaded rod (73c) in contact with the said nut (74a, 74c), and it also comprises a control circuit (fig. 8) for the motor, capable of delivering voltage pulses to the said motor, of a sufficient number to produce the drive of the carriage on the sole plate between two pre-determined portions of the surface thereof corresponding respectively to the high position and the low position of the sewing foot, the pulses being of a polarity characteristic of the direction of the drive.
13. A device according to claim 12, characterised in that the casing of the motor (73) is pivoted about a horizontal axis (73b) in such a manner that the threaded rod (73c) can follow the variations in position of the carriage (74) with respect to a horizontal reference plane during the movement of the carriage on the sole plate (70b) associated with the lever (70).

Images