Title of Invention

SEWING MACHINE WITH A DAMPING DEVICE

Abstract

The invention relates to a sewing machine which comprises a stationary sleeve (41) enclosing an oscillating shaft (38) in order to dampen the torsional oscillations of the latter. Between the shaft (38) and the sleeve (41) a gap (43) is configured. Said gap (43) is filled with a viscous substance (24) and is closed by sealing elements (44). When the shaft (38) is moved relative the sleeve (41) a viscous friction occurs in the viscous substance and brings about a damping effect.

Full Text

The invention relates to a sewing machine comprising oscillating and intermittently moved gear parts and at least one damping device to reduce oscillations triggered by the gear parts. It is known that in sewing machines, those shafts which drive oscillating or intermittently moved stitch pattern or feed means have a tendency to torsional oscillations. Such oscillations or vibrations can on the one hand lead to premature wear of the gear parts concerned and on the other hand cause overshoots of the stitch pattern and feed means so that, for example, zig-zag movements of the needle bar develop inaccurately or in the case of sewing machines with a fabric feeder which executes square movements, the feed length and therefore the stitch length are increased with increasing speed of the sewing machine. DE-AS 1 012 809 discloses a plurality of proposals for damping such torsional oscillations. Thus, Fig. 13 shows a damping device for an oscillating shaft which has a sleeve enclosing the shaft. One end of the sleeve is fixedly connected to the shaft whilst the other end is in frictional communication with the shaft wherein the magnitude of the frictional force can be adjusted. When the oscillating shaft is twisted into itself under the action of torsional forces, this results in a friction-affected relative movement between the oscillating shaft and the end of the sleeve connected thereto in frictional contact. The resulting braking effect damps the formation of torsional oscillations. However, such a damping device has a decisive disadvantage. Since wear and frictional corrosion occur at the frictional-contact connection between the sleeve and _ 2 - oscillating shaft, the adjusted frictional force gradually changes so that it must be continually reset to ensure the desired damping effect. In addition, when a certain wear limit is exceeded, the shaft and/or the sleeve must be exchanged. Figure 6 of DE-AS 1 012 809 shows a disk damper. This has a loose, rotatably arranged disk-shaped inertia member on a hub of the arm shaft which is surrounded by a closed housing filled with a viscous substance, which is fixedly connected to the arm shaft. When the housing rotates, the inertia member is taken along at substantially the same speed. When the arm shaft is twisted into itself under the action of torsional forces, the inertia member counteracts the resulting changes in direction and speed and in this way damps the formation of torsional oscillations. Since the inertia member must have a comparatively large diameter and a relatively large mass to achieve a sufficient damping effect, the space required for the disk damper is very large which makes it almost impossible to accommodate inside the machine housing. The very much more recent US-A6 058 862 relates to a drive mechanism for the needle-bar pendulum of a zig-zag sewing machine. Various solution variants are disclosed for damping the gear sections of this drive mechanism. In the first version of a damping device shown in Figs. 2 to 5, the lower fork-shaped end of an oscillating shaft is supported on a pivotally mounted eccentric pin which in turn is rotationally elastically fixed by means of a radially distant leaf spring. As a result of the continuing change in the direction of rotation of the drive member for the swinging lever, reaction forces produced at the lower end of the lever bring about a twisting of the eccentric pin and thus a bending of the leaf spring. This in turn causes relative movements between the leaf spring and two - 3 - bead-shaped counterbearings. These relative movements are very slight but can lead to premature wear as a result of the accompanying frictional corrosion. In addition, this type of damping device is very expensive to produce and assemble. In many other versions of a damping device disclosed in US-A 6 058 862 the eccentric pin, the leaf spring or the swinging lever are mounted by means of elastic hard-rubber components on the housing side. Since such components are subject to a hysteresis effect, the transmission accuracy of the drive movements is thereby impaired. The object of the invention is to provide an oscillation damping device for sewing machines with oscillating and intermittently moved stitch pattern and feed means, which has a space-saving design and operates reliably and largely free from wear. The object is solved by the features specified in claim 1. The overriding solution idea of the invention is to prevent the additional oscillating movements superimposed on the working movement of the gear sections which are oscillating or, for example, intermittently moved in the longitudinal direction, by means of a liquid damping, wherein a rotatably or translationally moved gear section of the drive mechanism of a stitch pattern and/or a feed means is so tightly surrounded by a capsule so as to form a gap which is only narrow but has the largest possible area, which is filled with a viscous substance and then tightly sealed. The damping effect in this case is based on the displacements which take place under a certain expenditure of force inside the viscous substance between the boundary layers at the surfaces of the gap. The viscous friction which takes place in the viscous substance in this case is - 4 - proportional to the velocity. This means that in the case of a movement beginning from a standstill, there is initially no motion resistance . This only builds up as the increasingly faster movement progresses and reaches its maximum when the motion velocity has reached its maximum. Thus, since in the case of viscous friction unlike mechanical friction, no initial adhesive friction needs to be overcome, ideal conditions exist for the damping of oscillations and specifically over the entire speed range of the sewing machine. Since the damping device according to the invention substantially only consists of a capsule surrounding the gear section to be damped, which is arranged to form the very narrow gap at a very small distance from the gear section, it is basically possible to have a very space-saving design. Such space-saving damping devices can thus even be arranged at those points in the housing where the available space is already largely filled with built-in devices and/or gear sections. The fundamental configuration of the damping device according to the invention for an oscillating shaft is specified in claim 2, wherein the large area of the gap required for a good damping result can preferably be achieved by an elongated sleeve utilising the given length of the shaft. This can be achieved according to claims 3 and 4 with the oscillating shaft for the needle bar pendulum mounted in the housing arm and with the slider shaft for the fabric feeder drive arranged in the base plate by extending the respective sleeve over the greatest possible distance between the respective bearing points of the shaft or pivot points of other gear sections. Since in this case the shafts remain largely unchanged, their inertia ratios are also unchanged. - 5 - If the shaft, as proposed in claim 5, is supported via roller bearings against the sleeve, when constructing the damping device there is no need to pay attention to the requirements when configuring a shaft bearing. If, on the other hand, the damping device is at the same time constructed as a sliding bearing for the shaft, in addition to the suitable material combination care must also be taken to ensure that the viscous substance possesses good lubricating properties in addition to the damping property. In order to compensate for the negative viscosity-temperature behaviour of fluids in general and thus the viscous substance also, it is proposed according to claims 7 and 8 to make the components forming the gap from materials having different thermal expansion coefficients. Thus, if the viscous substance becomes more liquid with increasing temperature of the sewing machine, the gap becomes narrower as a result of using materials having different expansion coefficients so that in this way, the degree of damping remains substantially constant over a larger temperature range. If, as is proposed in claim 9, a light metal tube is arranged on the shaft with the aid of pins such that an active outer gap and a passive inner gap are formed, in cases where constriction of the active outer gap occurs as a result of an increase in temperature, the viscous substance displaced therefrom can escape into the passive inner gap. The further development according to claim 10 provides the possibility for simple and rapid re-filling or after-filling of the gap with the viscous substance. If a gear section whose oscillations are to be damped is too short to achieve a sufficiently large gap area using a sleeve, according to claims 11 and 12, in addition to the - 6 - circumferential-side radial gap or instead of this gap, it is possible to arrange one or a plurality of axial gaps by arranging one or a plurality of pairs of disks in a correspondingly constructed chamber of the sleeve. After filling the chamber with said viscous substance, the axial gap or gaps exert an oscillation-damping effect similar to a radial gap on the circumference side. In claim 13 the fundamental embodiment of the damping device according to the invention is specified for a linearly intermittently moved slide. The invention is explained in detail with reference to a plurality of exemplary embodiments shown in the drawings. In the Figures: Figure 1 is a schematic diagram of stitch pattern and feed means of a sewing machine with damping devices for oscillating gear sections,, Figure 2 is an enlarged schematic view of the needle bar pendulum and the associated oscillating shaft with a damping device, Figure 3 is an enlarged sectional view along the line III-III in Fig. 2, Figure 4 is an enlarged schematic view of the sliding shaft with a damping device. Figure 5 is a schematic view of the sliding shaft according to Fig. 4 with a first variant of the damping device, Figure 6 is an enlarged sectional view along the line VI-VI in Fig. 5, - 7 - Figure 7 is a schematic view of the sliding shaft according to Fig. 4 with a second variant of the damping device, Figure 8 is an enlarged detail of Fig. 7, Figure 9 is a schematic view of the sliding shaft according to Fig. 4 with a further development of the damping device, Figure 10 is a schematic view of the sliding shaft with a damping device having an axial gap, Figure 11 is an enlarged sectional view of the damping device from Fig. 10, Figure 12 is a schematic view of the drive mechanism of a button clamp with a damping device for an intermittently moved slide, Figure 13 is a sectional view along the line XIII-XIII from Fig. 12, Figure 14 is a sectional view along the line XIV-XIV from Fig. 13. The housing 1 of a sewing machine shown by the dot-dash line in Fig. 1 consists of a base plate 2, a pedestal 3 and an arm 4 which goes over into a head 5. Mounted in the arm 4 is an arm shaft 6 which at its one end bears a belt pulley 7 which at the same time serves as a hand wheel and at its other hand bears a crank 9 provided with a mass compensating weight 8. The crank 9 is on the one hand operatively connected to a needle bar 11 mounted in a needle bar pendulum 10 and on the other hand, to a needle thread take-up lever 12. Affixed in the needle bar 11 is a thread-guiding needle 13. This operates in a known - 8 - fashion with a gripper not shown, arranged in the base plate 2. The needle bar pendulum 10 is a component of a needle transport mechanism 14. This has an oscillating shaft 15 arranged in the arm 14, whose one end is connected via a crank 16 to the needle bar pendulum 10 and whose other end is connected via a crank 17 to an eccentric rod 18. The eccentric rod 18 can be driven by a stepping motor 19. Associated with the oscillating shaft 15 is a damping device 20. This has an elongated sleeve 21 which surrounds the shaft 15 and,is affixed to the housing 1 by means of headless screws 22. A long annular gap 23 approximately 0.05 mm thick is formed between the sleeve 21 and the shaft 15. The gap 23 is filled with a viscous substance 24, for example, a high-viscosity chain lubricant, and is sealed at both ends using an O-ring 25. For better clarity Figs. 2 and 3 only show a small part of the substance 24 which in practice completely fills the gap 23. The sleeve 21 at the same time serves as a support for the shaft 15, said shaft being supported against the sleeve 21 by means of two needle bearings 26. In order to achieve a space-saving design, the needles 27 retained in needle cages roll on the one hand directly on the shaft 15 and on the other hand directly on the inner circumferential side of each larger-diameter hole 28 of the sleeve 21. 29 is an adjusting ring which is used to fix the axial position of the shaft 15. The arm shaft 6 is in operative connection with a lower main shaft 31 mounted in the base plate 2, via a belt drive 30. The shaft 31 at the same time serves as a lifting shaft which, by means of an eccentric drive 32, produces lifting - 9 - movements for a fabric feeder 33 which is arranged on a fabric feeder supporting bar 34 . An eccentric drive 35 arranged on the shaft 31 is connected to a hinged stitch regulator 36. A crank 37 which serves as the drive member of the hinged stitch regulator 3 6 is affixed to one end of the sliding shaft 38. Affixed to the other end of the sliding shaft 3 8 is a crank 3 9 which is hinge-mounted on the fabric feeder supporting bar 34 and imparts pushing movements to the fabric feeder 33. Associated with the sliding shaft 38 is a damping device 4 0 which in principle corresponds to the damping device 20 for the oscillating shaft 15. The damping device 40 accordingly has an elongated sleeve 4 1 which encloses the shaft 38 and is affixed to the base plate 2 by means of a threaded pin 42. A long annular gap 43 about 0.05 mm thick is formed between the sleeve 41 and the shaft 38. The gap 43 is filled with the same viscous substance 24 as the gap 23 and is sealed at its ends using an O-ring 44. The sleeve 41 also serves as a support for the shaft 38, said shaft being supported against the sleeve 41 by means of two needle bearings 45. The needles 46 retained in needle cages roll on the shaft 38 and on the inner circumferential side of each hole 47 of the sleeve 41. When the sewing machine is operating, a motor, not shown, which is drivably connected to the belt pulley 7, sets the arm shaft 6 in rotary motion. This is transmitted via the belt pulley 30 to the lower main shaft 31 and causes the fabric feeder 33 to make a square movement composed of lifting and pushing movements. In this case, the length of the pushing movement and thus the magnitude of feed of the fabric feeder 33 or the stitch length of the seam to be made is specified by suitably adjusting the stitch regulator 36. At the same time the stepping motor 19 drives the needle transport mechanism 14 and when the needle 13 - 10 - has pierced the fabric to be sewn, brings about a feed movement of the needle bar 11 running synchronously with the feed movement of the fabric feeder 33. The two damping devices 20 and 40 have the effect that during the oscillating rotary movement of the two shafts 15 and 38 in the gaps 23, 43, viscous friction takes place in the viscous substance 24 whose magnitude depends on the thickness of the gap 23, 43, the size of the gap area and on the viscosity of the substance 24. In this case, the viscous friction takes place both during the working movement to be executed by the shafts 15, 38, i.e. the feed movement to be executed, and also during the uncontrolled torsional oscillation superimposed thereon. In this case, the working movement of the shafts 15, 38 is executed precisely in time and distance by the stepping motor 19 and the stitch regulator 36 whilst overcoming the viscous friction. On the other hand, the viscous friction retards the striving of the shafts 15, 38 to turn further beyond the motion reversal point specified by the set feed magnitude of the needle bar 11 and the fabric feeder 33 and in this way additionally damps superimposed torsional oscillations. Figures 5 and 6 show, with reference to the damping device 40, a damping device 40.1 in which the negative viscosity-temperature behaviour of the viscous substance 24 is compensated. For this purpose, a tube 48 made of light metal, e.g. aluminium, is pulled onto the sliding shaft 38 made of steel, which tube is connected rotationally fixedly to the shaft 38 using a through pin 49 and an adjusting spring 50. The gap 51 filled with the viscous substance 24 is constructed between the light metal tube 4 8 and the inside of the sleeve 41 made of steel. With increasing temperature, the viscosity of the viscous substance 24 decreases, i.e. it becomes somewhat more -1l- liquid whereby its viscous frictional resistance decreases. As a result of the higher coefficient of thermal expansion of light metal compared with the expansion coefficient of steel, the gap 51 becomes narrower with increasing temperature whereby in turn the viscous frictional resistance inside the gap 51 is increased. Since the effect of the temperature-induced change in the gap thickness is oppositely directed to the effect of the temperature-induced change in the viscosity, the two effects at least partially compensate for each other so that in the damping device 40.1 the degree or extent of the oscillation damping remains largely constant over a larger range of temperature. In the damping device 40.1, during a narrowing of the gap 51 some of the viscous substance 24 is displaced in the axial direction towards the O-ring 44 which is why this should preferably be displaceably arranged. In the damping device 40.2 shown in Figs. 7 and 8 which refers to the damping device 40.1, a special solution is proposed for receiving the viscous substance 2 4 expelled during the narrowing of the gap 51. In this case, it is provided that the light metal tube 48.1 likewise connected rotationally fixedly to the shaft 38 with the aid of a pin 49 and an adjusting spring 50, not only forms an outer gap 51 with respect to the sleeve 41 but at the same time forms an inner gap 52 with respect to the shaft 38. The gaps 51, 52 are interconnected by a plurality of cross-holes 53. Since the viscous friction only takes place in the outer gap 51, this is an active gap whereas the inner gap 52 is a passive gap. If the outer gap becomes increasingly narrow with increasing temperature as a result of the higher coefficients of thermal expansion of light metals, the viscous substance 24 displaced from it can flow through the cross-holes 53 into the inner gap 52 which is becoming larger as a result of the influence of temperature. With decreasing temperature, the direction of flow is reversed. - 12 - Figure 9 shows a further variant relating to the damping device 40 from Fig. 4. In this damping device 40.3 the shaft 38.1 has a longitudinal hole 54 which is in communication with the gap 43 between the shaft 38.1 and the sleeve 41 through cross-holes 55. The end of the longitudinal hole 54 is sealed by a lubricating nipple 56 acting as a check valve. In this damping device 40.3 the gap 4 3 can be filled with the viscous substance 2 4 in a particularly easy fashion and if necessary re-filled if some of the viscous substance 24 should escape from the gap 43 and past the O-rings 44. The damping device 57 shown in Figs. 10 and 11 is in this case associated with the sliding shaft here designated as 38.2 on which the crank 39 is fixedly clamped by means of clamping rings 58. The shaft 38.2 is mounted in a sleeve 59 arranged fixedly to the housing by means of two needle bearings 4 5. The sleeve 5 9 has a chamber 60 which is enlarged in the radial direction and open on one side. The interior transversely running wall 61 of the chamber 60 is in alignment with a shoulder 62 of the shaft 38.2. Arranged on the shaft 38.2 in the area of the chamber 60 are a plurality of disks 63 which are separated from one another by spacer rings 64. The shaft-side disks 63 are pressed against the shoulder 62 of the shaft 38.2 by means of a screw 65, a pressure ring 66, the already mentioned clamping rings 58, an intermediate ring 67 and a further intermediate ring 68 whereby they are connected rotationally fixedly to the shaft 38.2. A plurality of sleeve-side disks 69 engage between the shaft-side disks 63, which are also separated from one another by spacer rings 70. The disks 69 are pressed by a screw ring 71 against the wall 61 of the chamber 60 whereby they are connected rotationally fixedly to the sleeve 59. - 13 - Narrow axial gaps 72 are formed between the wall 61 and the neighbouring disk 63 and the other disks 63 and 69 arranged next to one another in rows. The chamber 60 and therefore also the gap 72 are filled with the viscous substance 24. For better clarity in this exemplary embodiment in Fig. 11 only a small part of the substance 24 is shown which in practice completely fills the gap 72 and the remaining cavities of the chamber 60. The chamber 60 is sealed by an O-ring 73 between the screw ring 71 and the intermediate ring 68 and by an O-ring 7 4 between the sleeve 5 9 and the shaft 38.2. When the sewing machine is operating, a relative movement takes place between the stationary sleeve-side disks 69 and the oscillating shaft-side disks 63. The damping device 57 has the effect that in this case, viscous friction occurs in the viscous substance 24 in the gaps 72 whose magnitude as in the previously described damping devices 2 0 and 4 0, depends on the thickness of the gap 72, the size, i.e., in this case the sum of the gap areas and the viscosity of the substance 24. Thus the damping device 57 also brings about a damping of any torsional oscillations of the sliding shaft 38.2 and thereby reduces the risk of overshoot of the fabric feeder 33. In Fig. 12 a button hole sewing machine is shown schematically and only partly. Its housing 80 shown by the dot-dash line consists of a base plate 81, a pedestal 82 and an arm 83 which goes over into a head 84. Mounted in the arm 83 is a supporting rod 8 5 which can be moved up and down for a guide 8 6 of a sewing material holder 87. The guide 86 has a guide plate 88 having a U-shaped cross-section which is affixed to the supporting rod 8 5 by means of two intermediate pieces 8 9 and a support plate 90. Screwed onto the underside of the guide plate 88 is a flat stop plate 91 which together with the guide plate -14- 86 forms a guide channel 92 (Fig. 14). Mounted in the guide channel 92 is a slide plate 93 movable in the longitudinal direction. Screwed onto the upper side of the slide plate 93 is a support block 94 which extends upwards through an oblong recess 95 inside the guide plate 88. Screwed onto the support block 94 is an angled support arm 96 which carries the footplate 97 of the sewing holder 8 7 at its other end. A driving rod 9 9 is hinge-mounted to the support block 94 via a bearing bolt 98. The other end of the driving rod 99 is connected to a crank 100 which is affixed to the shaft 101 of a stepping motor 102 arranged in the housing 80. Between the inside of the guide plate 88 and the stop plate 91 on the one hand and the slide plate 93 on the other hand are narrow gaps 103 which are filled with a viscous substance 104 . Since the guide plate 8 8 and stop plate 91 jointly with the slide plate 93 form a sliding bearing, in this case the substance 104 must not only have a high viscosity and thus be viscous but it must also have good lubricating properties. A high-viscosity chain lubricant is suitable for this purpose. For sealing the guide 86 there is provided a flat bath 105 which tightly encloses the underside of the stop plate 91 and the side walls of the guide plate 88 and is affixed to the guide plate 88 by means of a plurality of screws 106. The recess 95 is sealed by means of a flat cover plate 107 which is affixed to the support block 94. Two flat compensating channels 108 running in the longitudinal direction are constructed on the upper side of the slide plate 93. The guide 8 6 together with the gaps 103 filled with the viscous substance 104 and the bath 105 as well as the cover plate 107 form a damping device 109. - 15 - The intermittent rotary movement caused by the stepping motor 102 is transferred via the crank 100 and the driving rod 99 into an intermittent longitudinal movement of the slide plate 93 inside the fixed guide 86 whereby the sewing holder 87 executes feed movements corresponding to the desired stitch length. The damping device 10 9 has the effect that during the intermittent movement of the slide plate 93 in the gaps 103 a viscous friction takes place in the viscous substance 104 whose magnitude depends on the thickness of the gap 103, the size, i.e., in this case the sum of the gap areas and on the viscosity of the substance 104. In this way the damping device 109 is able to damp oscillations occurring within the drive pull between the shaft 101 and the slide plate 93 whereby overshoot of the sewing holder 87 is avoided. In this case, the compensating channels 108 serve to make it possible to equalise the pressure of the air enclosed in the guide 8 6 during the movement of the slide plate 93. Furthermore, in the end positions of the slide plate 93 the substance 10 4 expelled from the gaps 103 is pressed into the compensating channels 108 and from there is guided back again into the upper gap 103. As a result, a uniform distribution of the viscous substance 104 in all four gaps 103 should be made possible. 16 1. A sewing machine comprising a housing (1, 80), an oscillating or intermittently moved stitch pattern and feed means (15, 38; 93), gear sections mounted inside the housing (1; 80), connected to the stitch pattern and feed means (15, 38; 93), which generate or transfer the oscillating or intermittent movement, at least one Elongated capsule (21, 41; 59; 86) arranged fixedly in the housing which surrounds one of the oscillating or intermittently moved components (15, 38,- 93), a narrow large-area gap (23, 43; 51; 72; 103) constructed between the capsule (21, 41; 59; 8 6) and the component (15, 38; 93), a viscous substance (24; 104) filling the gap (23, 43; 51; 72; 103) and sealing elements (25, 44; 73, 74; 105, 107) to seal the gap (23, 43; 51; 72; 103). 2. The sewing machine according to claim 1, characterised in that the capsule for encasing or vibrational damping of an oscillating shaft (15, 38) is constructed as an elongated sleeve (21, 41; 59) which is sealed towards the shaft (15, 38) by means of two sealing rings (25, 44; 73, 74) provided in the area of its ends. -17- 3. The sewing machine according to claim 2, comprising a swinging-mounted needle bar (11) and an oscillating drive (17, 18) which is connected to a needle bar pendulum (10) via a shaft {15) mounted in the housing arm (4) , characterised in that the oscillating shaft whose oscillations are to be damped comprises the shaft (15) used to drive the needle bar pendulum (10) and that the sleeve (21) extends over the greatest possible distance inside the housing arm (4). 4. The sewing machine according to claim 2 or 3, which has as feed means, a fabric feeder (33) arranged on a fabric feeder support bar (34) which executes square movements by means of a lifting shaft (31) and an oscillating driven slide shaft (38), wherein a stitch regulator (36) is connected to the slide shaft (38) via a drive member (37), characterised in that the oscillating shaft whose oscillations are to be damped comprises the slide shaft (38) and that the sleeve (41) extends over the greatest possible distance between the pivot point of the drive member (37) of the stitch regulator (36) and the pivot point of a crank (39) to the fabric feeder support bar (34). 5. The sewing machine according to any one of claims 2 to 4, characterised in that the sleeve (21, 41; 59) is constructed as a support for the shaft (15, 38) whose oscillations are to be damped, wherein the shaft (15, 38) is supported with respect to the sleeve (21, 41; 59) by means of roller bearings (26, 45). 6. The sewing machine according to any one of claims 2 to 4, characterised in that the sleeve is constructed as part of an elongated sliding bearing wherein the viscous substance at the same time serves as lubricant for the sliding bearing. - 18 - 7. The sewing machine according to any one of claims 1 to 6, characterised in that the components {41, 48) forming the gap (51) are made of materials having different coefficients of thermal expansion whereby a narrowing of the gap (51) is obtained when the temperature rises. 8. The sewing machine according to any one of claims 2 to 6 in conjunction with claim 7, characterised in that the shaft (38) and the sleeve (41) consist of steel and that a light metal tube (48) is arranged rotationally fixedly on the shaft (38). 9. The sewing machine according to claim 8, characterised in that the light metal tube (48.1) is affixed to the shaft (38) by means of a transversely running pin (49) and an adjusting spring (50) and that between the outside of the light metal tube (48.1) and the sleeve (41) an active gap (51) is formed and between the inside of the light metal tube (48.1) and the shaft (38) a passive gap (52) is formed and that the gaps (51, 52) are interconnected by cross-holes (53). 10. The sewing machine according to any one of claims 1 to 9, characterised in that the shaft (38.1) has a longitudinal hole (54) which is sealed by a lubricating nipple (56) which acts as a check valve and is in communication with the gap (43) by means of at least one transverse hole (55). 11. The sewing machine according to any one of claims 2 to 10, characterised in that in addition to a radial gap or instead of a radial gap in a radially enlarged chamber (60) of the sleeve (59) there is arranged at least one disk (63, 69) connected rotationally fixedly to the shaft (38.2) and at least one further disk connected rotationally fixedly to the sleeve (59) such -19 - that a narrow axial gap (12) is formed at least between the two disks (63/ 69) and that the chamber (60) and the at least one gap (72) are filled with a viscous substance {24). 12. The sewing machine according to claim 11, characterised in that a plurality of shaft-side disks (63) separated from one another by spacer rings (64) are braced against one shoulder (62) of the shaft (38.2) by means of a screw (65) and that a corresponding number of sleeve-side disks (69) also separated from one another by spacer rings (70) , which engage between the shaft-side disks (63) are pressed against a wall (61) of the chamber (60) by means of a screw ring (71). 13. The sewing machine according to claim 1, characterised in that the capsule for enclosing or for vibrational damping of an intermittently moved carriage (slide plate 93) is constructed as a box (guide 86) whose inside forms the gap (103) with the neighbouring surface of the carriage (93). Dated this 14th day of FEBRUARY 2005 The invention relates to a sewing machine which comprises a stationary sleeve (41) enclosing an oscillating shaft (38) in order to dampen the torsional oscillations of the latter. Between the shaft (38) and the sleeve (41) a gap (43) is configured. Said gap (43) is filled with a viscous substance (24) and is closed by sealing elements (44). When the shaft (38) is moved relative the sleeve (41) a viscous friction occurs in the viscous substance and brings about a damping effect.

Documents:

00178-kolnp-2005-abstract.pdf

00178-kolnp-2005-claims.pdf

00178-kolnp-2005-correspondence-1.1.pdf

00178-kolnp-2005-correspondence-1.2.pdf

00178-kolnp-2005-correspondence-1.3.pdf

00178-kolnp-2005-correspondence.pdf

00178-kolnp-2005-description(complete).pdf

00178-kolnp-2005-drawings.pdf

00178-kolnp-2005-form-1.pdf

00178-kolnp-2005-form-18.pdf

00178-kolnp-2005-form-2.pdf

00178-kolnp-2005-form-3.pdf

00178-kolnp-2005-international publication.pdf

00178-kolnp-2005-international search authority report.pdf

00178-kolnp-2005-pa.pdf

00178-kolnp-2005-pct others.pdf

00178-kolnp-2005-priority document.pdf

178-kolnp-2005-granted-abstract.pdf

178-kolnp-2005-granted-claims.pdf

178-kolnp-2005-granted-correspondence.pdf

178-kolnp-2005-granted-description (complete).pdf

178-kolnp-2005-granted-drawings.pdf

178-kolnp-2005-granted-form 1.pdf

178-kolnp-2005-granted-form 18.pdf

178-kolnp-2005-granted-form 2.pdf

178-kolnp-2005-granted-form 26.pdf

178-kolnp-2005-granted-form 3.pdf

178-kolnp-2005-granted-form 5.pdf

178-kolnp-2005-granted-letter patent.pdf

178-kolnp-2005-granted-reply to examination report.pdf

178-kolnp-2005-granted-specification.pdf

178-kolnp-2005-granted-translated copy of priority document.pdf