Sewing machine with a spacer element, and use of a spacer element in a sewing machine

Abstract

The invention relates to a sewing machine comprising: a stitch plate (1) on which a fabric can be arranged; a presser foot (2) designed to hold the fabric; and a presser foot bar (3) to which the presser foot (2) is attached. The sewing machine further comprises a spacer element (5), the spacer element (5) being designed and arranged such that it establishes a minimum distance (h) between the stitch plate (1) and the presser foot (2). The invention further relates to the use of a spacer element (5) in a sewing machine to establish a minimum distance (h) between the stitch plate (1) of the sewing machine and the presser foot (2) of the sewing machine.

Description

Technical area

[0001] The present invention relates to a sewing machine having at least one needle plate, a presser foot, and a presser foot bar. Furthermore, the invention relates to the use of a spacer element in a sewing machine. State of the art

[0002] Sewing machines generally serve to mechanically create a seam. For example, sewing machines are used in the automotive industry to add seams or decorative stitching to leather items. In particular, car seats, instrument panels, or door panels are equipped with such seams or decorative stitching. The seams or decorative stitching primarily serve as a decorative element, intended to give the leather item a high-quality visual impression or at least enhance such a look.

[0003] However, this can only be achieved if the seam is applied to the leather object in a visually uniform and consistent manner, without damaging the object or adversely altering its appearance. However, the latter point in particular continues to pose a major problem when using conventional sewing machines.

[0004] For example, common sewing machines feature a presser foot designed to hold the leather item being sewn, ensuring precise and even transport of the fabric placed on a needle plate beneath the sewing machine. This presser foot rests on the needle plate, and a presser foot pressure, often continuously adjustable, can be set. This pressure acts on the presser foot via a presser foot bar. The correct presser foot pressure to be used usually depends on the fabric being sewn. For soft materials, such as cloth, a lower pressure is used, while for firm materials, such as leather, a higher pressure is required. With the correct presser foot pressure setting, the fabric will not slip and will be transported smoothly.

[0005] DE 90 984 C discloses a lifting device for a fabric presser of a sewing machine, wherein the lifting device has a plurality of elements and is adjustable to different fabric thicknesses.

[0006] However, when creating seams on high-quality leather items, the current adjustment options for the fabric presser foot are insufficient to achieve satisfactory results. If the pressure is set low, the fabric slips and is not fed evenly. If the pressure is set higher, however, the fabric presser foot leaves a visible mark on the leather item, which no longer meets the desired aesthetic requirements. Description of the invention

[0007] The invention is therefore based on the object of providing a sewing machine that eliminates the above-mentioned problems and disadvantages of the prior art. In particular, the object of the present invention is to provide a sewing machine that enables a sewing material, in particular a leather item, to be provided with seams in such a way that the result meets high aesthetic standards and, in particular, that no visible marks are left on the sewing material by the presser foot of the sewing machine.

[0008] The invention is further based on the object of providing an element for use in sewing machines which eliminates the above problems and disadvantages of the prior art.

[0009] The solution according to the invention consists in specifying a sewing machine which has the following: a throat plate on which a sewing material can be arranged; a fabric presser foot which is designed to hold the sewing material; and a presser foot bar to which the fabric presser foot is attached, wherein the sewing machine further comprises a spacer element, wherein the spacer element is designed and arranged such that the spacer element specifies a minimum distance h between the throat plate and the fabric presser foot.

[0010] The fabric, such as a leather item, can be placed on the needle plate. The fabric presser foot is designed to hold the fabric in place. This means the fabric does not slip during sewing and is pressed toward the needle plate. The fabric presser foot also supports even fabric feeding. When sewing leather, this is usually achieved using the triple-feed principle, in which a specially designed feeding foot presses the fabric from above against a feed dog located beneath the needle plate. This then grips the fabric and feeds it forward.

[0011] To ensure this process, however, pressure must be exerted on the fabric from above via the presser foot bar and fabric presser foot. The presser foot bar typically operates under spring pressure, allowing the fabric presser foot to press elastically against the fabric.

[0012] The sewing machine according to the invention satisfactorily achieves this objective. In particular, the minimum distance h between the needle plate and the presser foot ensures that the presser foot no longer leaves an imprint on the fabric. At the same time, the fabric is held securely, preventing it from slipping and allowing it to be transported evenly.

[0013] The minimum distance h is parallel to an axial direction of the presser foot bar between the presser foot and the throat plate.

[0014] In addition, the presser foot bar of the sewing machine according to the invention has a stop element which comes into contact with the spacer element.

[0015] Through this stop, the stop element and the spacer element specify the minimum distance h. The stop element can, for example, be a flange on an end of the presser foot bar opposite the fabric presser foot. Such flanges are often already formed on the end of the presser foot bar, for example, for force transmission. Alternatively, it can also be a collar or other element, such as a rod-shaped element, that protrudes outward from the presser foot bar.

[0016] The spacer element is arranged between a head element of the sewing machine and the stop element of the presser foot bar.

[0017] The sewing machine head is located above the needle plate. The head can be, for example, part of the housing of a sewing machine head.

[0018] Alternatively or additionally, it would also be conceivable for the guide sleeve to rest on a guide sleeve located in or on the head element to guide the presser foot bar in its movement. Alternatively, it would be conceivable for the guide sleeve itself to be designed as a spacer element and to come into contact with the stop element.

[0019] According to an advantageous development of the invention, the spacer element is designed to be elastic at least in some areas.

[0020] This means that the spacer element can be compressed by the force exerted by the presser foot bar, slightly dampening the force and thus the pressure acting on the fabric. If the spacer element is elastic, it can be a spring element, such as a coil spring. Alternatively, it can also be a sleeve element made of an elastic material.

[0021] The cushioning effect of the spacer element allows the pressure acting on the fabric to be reduced to such an extent that the presser foot leaves no visible mark on the fabric. At the same time, the minimum distance h can be kept so small that the fabric is held securely and can be fed evenly.

[0022] According to an advantageous development of the invention, the spacer element is sleeve-shaped, wherein the presser foot bar is arranged in a sleeve interior of the spacer element.

[0023] A sleeve is particularly suitable for specifying the desired minimum distance h between the needle plate and the presser foot. The inner radius of the sleeve is smaller than the outer radius of the presser foot bar, so that the latter is guided within the sleeve but can also move axially, especially from top to bottom and vice versa.

[0024] If the presser foot bar also has a stop element, for example in the form of a flange, a collar or similar, the minimum distance h can be reliably specified.

[0025] Furthermore, a sleeve is inexpensive to manufacture and easy to install. In particular, it can be easily retrofitted to machines already in production. A soft metal alloy, such as a copper alloy, preferably brass, is particularly suitable as the material.

[0026] According to an advantageous development of the invention, the fabric presser foot has a friction layer on an underside facing the throat plate.

[0027] A friction layer is a layer that increases the coefficient of friction. This can be a coating applied to the presser foot. Alternatively, it can also be an additional plate-shaped element attached to the underside of the presser foot. A rubber material is particularly suitable.

[0028] The friction layer increases the friction between the fabric and the presser foot, thus preventing the fabric from slipping. By specifying the minimum distance h between the presser foot and the needle plate, the friction between the fabric and the presser foot is also reduced, since a normal force can only act on the fabric once the minimum distance h from the presser foot has been overcome. By applying the friction layer, the coefficient of friction between the presser foot and the fabric can be increased, ensuring that the fabric is still held securely in place.

[0029] The solution according to the invention further consists in specifying the use of a spacer element in a sewing machine in order to specify a minimum distance h between a needle plate of the sewing machine and a fabric presser foot of the sewing machine.

[0030] This offers the same advantages as the sewing machine according to the invention. However, it's worth emphasizing its retrofit capability. The spacer element can be retrofitted to standard sewing machines, allowing them to be easily and cost-effectively upgraded.

[0031] According to an advantageous development of the invention, the spacer element specified for use is designed to be elastic at least in some regions.

[0032] This allows the spacer element to be compressed, dampening the pressure exerted on the fabric. This can further improve the sewing result.

[0033] The spacer element specified for use comes into contact with a stop element of a presser foot bar of the sewing machine.

[0034] This is particularly a well-implemented option for specifying the minimum distance h. In particular, a stop of the spacer element with the presser foot on the upper side and a stop with a head element of the sewing machine on the opposite lower side are suitable.

[0035] According to an advantageous development of the invention, the spacer element specified for use is sleeve-shaped.

[0036] This allows the spacer element to be securely positioned around the presser foot bar during use. A reliable specification of the minimum distance h can thus be achieved. The size of the minimum distance h depends directly on the length in a rotational axis direction of the spacer element, in particular the sleeve. Thus, the minimum distance h can be simply specified by the length of the sleeve.

[0037] Further advantages of the invention will become apparent from the description and the drawings.

[0038] The invention will be explained in more detail below with reference to the description of exemplary embodiments and the accompanying drawings. Further advantageous embodiments and combinations of features of the invention will become apparent from the following description and the entirety of the patent claims. Short description of the drawings

[0039] The drawings used to explain the embodiments show: Fig. 1 is a schematic representation of a region of the sewing machine according to the invention in which a spacer element according to the invention is arranged; and Fig. 2 is a schematic plan view of a spacer element according to the invention. Ways to implement the invention

[0040] In the figures, directions "above" or "below" are used, which are from the perspective of a person looking from the side (as in Fig. 1) of the user looking at the sewing machine.

[0041] The Fig. 1 shows a schematic representation of an area of ​​the sewing machine according to the invention.

[0042] In detail, Figure 1 First, a needle plate 1, a presser foot 2, a presser foot bar 3, and a head element 4 of the sewing machine are shown. The fabric is placed on the needle plate 1 during a sewing process. A feed dog (not shown) can be arranged beneath the needle plate 1, which is designed to advance the fabric by the set stitch length after each stitch. Also not shown are, for example, the needle, needle bar, and feed foot.

[0043] The fabric presser foot 2 is responsible for pressing the fabric downward toward the needle plate 1 and holding it in position. With a triple feed, the feed foot can ensure that the fabric is fed evenly. Furthermore, the fabric is held taut to ensure a consistent stitch pattern.

[0044] This requires pressure to be applied from above onto the presser foot 2, pressing it downwards towards the needle plate 1. This pressure is applied as the indicated presser foot pressure P via the presser foot bar 3 onto the presser foot 2. The necessary power transmission elements and the power generation device, for example a pneumatic system, are housed in a sewing machine head, which is located in Fig. 1 is indicated as head element 4. The head element 4 can in particular be a part of a housing of the sewing machine head.

[0045] The head element 4 is typically located above the needle plate 1, so that the presser foot bar 3 extends from the head element 4 through the head element 4 downwards (in the direction of the needle plate 1) to the presser foot 2. For this purpose, the head element 4 has an optional guide sleeve 6 designed to guide the presser foot bar 3.

[0046] On currently common sewing machines, the presser foot pressure P presses the fabric presser foot 2 onto the needle plate 1 via the presser foot bar. This means that there is no gap between the fabric presser foot 2 and the needle plate 1 when no fabric is placed on the needle plate 1. If less pressure is required on the fabric, the presser foot pressure P is set accordingly lower. As described above, however, even this does not produce the desired sewing results.

[0047] In Fig. 1The sewing machine therefore also has a spacer element 5. In this embodiment, the spacer element 5 is sleeve-shaped. As shown in Fig. 1 As can be seen, the spacer element 5 is arranged above the presser foot 2 and in particular in the sewing machine head of the sewing machine.

[0048] The presser foot bar 3 runs inside the spacer element 5. The presser foot bar 3 has a (in Fig. 1 shown) upper area has a stop element 3a. The stop element 3a is pressed by the presser foot pressure P in the direction of the spacer element 5 and comes into contact with an upper area of ​​the spacer element 5.

[0049] The spacer element 5 itself is limited in a downward direction of movement. This can, for example, be achieved as shown in Figure 1As shown, this can be achieved by a lower region of the spacer element 5 resting on the head element 4. Alternatively or additionally, resting on the guide sleeve 6 would also be conceivable. A further alternative would be conceivable for the guide sleeve 6 itself to be designed as a spacer element 5. This would then extend upwards for a longer period. If the application refers to a spacer element 5, these aspects can thus also be applied to the correspondingly modified guide sleeve 6.

[0050] Coming back to the stop element 3a, this means that the stop element 3a does not move the spacer element 5 downwards per se, apart from an elastic behavior of the spacer element 5. The spacer element 5 thus provides a stopper structure for the stop element 3a and thus also for the presser foot bar 3 and the presser foot 2 attached to it.

[0051] This creates a minimum distance h between the needle plate 1 and the presser foot 2. More precisely, the minimum distance h is created between an upper side of the needle plate 1 and an underside of the presser foot 2. For the sake of completeness, it should be noted at this point that with a very high presser foot pressure P and the use of a highly elastic spacer element 5, the elastic spacer element 5 could be compressed to such an extent that the minimum distance h is no longer created. However, this should be considered an exception. This minimum distance h is created during normal operation.

[0052] The minimum distance h created by the spacer element 5 prevents the presser foot 2 from leaving marks on the fabric. At the same time, sufficient pressure can be exerted on the fabric so that it does not slip and can be transported evenly.

[0053] To further prevent the fabric from slipping and to improve the feed, a hole can be made on the underside of the presser foot 2, as shown in Fig. 1 As shown, a friction layer 2a may be arranged to increase friction with the fabric. The effect of the friction layer 2a interacts synergistically with that of the spacer element 5.

[0054] The spacer element 5 is in Fig. 2 shown once again more clearly. Fig. 2 a schematic plan view of the spacer element 5 according to the invention. The spacer element 5 is sleeve-shaped and has an upper region 5a and a lower region 5b.

[0055] The upper region 5a has an outer radius that is smaller than the outer radius of the lower region 5b. A transition region is formed between the two regions 5a and 5b, connecting the two outer radii.

[0056] Furthermore, a sleeve interior is formed within the spacer element 5. The sleeve interior is defined by the inner circumferential walls of the spacer element 5. Like the outer radius, the inner radius of the spacer element 5 can vary along the length of the spacer element 5. In particular, the inner radius in the upper region 5a can be smaller than the inner radius in the lower region 5b. This would result in the wall thickness of the sleeve-shaped spacer element 5 being uniform despite different outer radii. Such a spacer element 5 is particularly easy to manufacture from a tubular starting element. The starting material must allow for a certain degree of deformability, so a soft metal such as brass is preferably selected.

[0057] However, the smallest inner radius of the spacer element 5 is always large enough to surround the presser foot bar 3 without interference. "Interference-free" here means that the presser foot bar 3 still has sufficient play in the spacer element 5. The presser foot bar 3 can therefore, as shown in Figure 1 shown, can be arranged movably within the spacer element 5.

[0058] The spacer element 5 may further comprise a fastening element (not shown) that serves to secure the spacer element 5 to a predetermined position within the sewing machine. The fastening element is preferably a threaded element. LIST OF REFERENCE SYMBOLS

[0059] 1Stitch plate 2Presser foot 2aFriction layer 3Presser foot bar 3aStop element 4Head element 5Spacer element 5aUpper area (of the spacer element) 5bLower area (of the spacer element) 6Guide sleeve (for the presser foot bar) hMinimum distance (between stitch plate and presser foot) PPresser foot pressure

Claims

1. Sewing machine comprising: - a needle plate (1), on which a sewing item can be placed; - a fabric-presser foot (2), which is designed to hold the sewing item; and - a presser bar (3), to which the fabric-presser foot (2) is attached, wherein the sewing machine also has a spacer element (5), wherein the spacer element (5) is designed and arranged in such a way that the spacer element (5) predefines a minimum distance (h) between the needle plate (1) and the fabric-presser foot (2), wherein the presser bar (3) has a stop element (3a), which comes into abutment with the spacer element (5), characterized in that the spacer element (5) is arranged between a head element (4) of the sewing machine and the stop element (3a) of the presser bar (3).

2. Sewing machine according to Claim 1, wherein the spacer element (5) is of elastic design at least in certain regions.

3. Sewing machine according to one of the preceding claims, wherein the spacer element (5) is designed in the form of a sleeve, and wherein the presser bar (3) is arranged in a sleeve interior of the spacer element (5).

4. Sewing machine according to one of the preceding claims, wherein the fabric-presser foot (2) has a friction layer (2a) on an underside, which points toward the needle plate (1).

5. Use of a spacer element (5) in a sewing machine in order to predefine a minimum distance (h) between a needle plate (1) of the sewing machine and a fabric-presser foot (2) of the sewing machine, wherein the sewing machine comprises the following: - a needle plate (1), on which a sewing item can be placed; - a fabric-presser foot (2), which is designed to hold the sewing item; and - a presser bar (3), to which the fabric-presser foot (2) is attached, wherein the spacer element (5), when used, comes into abutment with a stop element (3a) of the presser bar (3) of the sewing machine, characterized in that the spacer element (5) is arranged between a head element (4) of the sewing machine and the stop element (3a) of the presser bar (3).

6. Use of a spacer element (5) in a sewing machine according to Claim 5, wherein the spacer element (5) is of elastic design at least in certain regions.

7. Use of a spacer element (5) in a sewing machine according to either of Claims 5 and 6, wherein the spacer element (5) is designed in the form of a sleeve.

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