WO1989001067A1

WO1989001067A1 - Sewing machine with top transport device

Info

Publication number: WO1989001067A1
Application number: PCT/EP1988/000414
Authority: WO
Inventors: Kurt Klundt
Original assignee: Pfaff Industriemaschinen Gmbh
Priority date: 1987-07-27
Filing date: 1988-05-13
Publication date: 1989-02-09
Also published as: EP0368869B1; DE3724786A1; EP0368869A1; JPH02504345A; DE3902443A1; DE3870244D1; DE3724786C2; KR890701824A; ES2008505A6

Abstract

In known height-adjustment systems, the height of the pressure foot system cannot be easily adjusted to adapt to variations in fabric thickness. In the new arrangement, adjustment is automatic. To achieve automatic adaptation, the drive connection between the top transport foot and the pressser foot is designed as a sequential regulator. The sequential regulator is preferably a hydraulic regulator (27, 27') secured to the housing of the sewing machine and contains an adjusting piston (22, 22') and a sequential piston (26) which are held together by a measuring element designed as a spring (119, 125 or 201, 205 or 210, 212) in order to utilize the reaction forces on the stitching feet during the stitching process. The sequential regulator can be used for various types of top transport devices in sewing machines.

Description

Sewing machine with a top feed device

The invention relates to a sewing machine according to the preamble of claim 1.

In a known sewing machine of this type (DE-GM 7 123 663), the stroke of the presser system can only be adjusted by the operator while the sewing machine is at a standstill. The stroke is usually set according to the thickest part of the sewing material to be sewn over so that no difficulties arise during sewing. However, the larger the stroke, the greater the tendency of the feed and presser elements to vibrate at higher sewing speeds. In addition to other undesirable effects, they can temporarily lose contact with the sewing material, which means that even transport in the selected stitch length is no longer guaranteed.

In this sewing machine, the presser bar, which is under the pressure of the presser spring, is supported on an adjustable stop. The presser feet, d. H. the presser foot and the upper feed foot have only a low mass inertia and are cushioned separately from the presser system so that at least one presser foot always has sufficient contact with the material.

When successively sewing different heights, problems with level adjustment arise. This must be readjusted by hand in order to prevent the presser bar from moving during normal sewing Stop takes off. There are then completely different presser ratios because the presser system then loses the desired low inertia. If the fabric thickness changes beyond the stroke limitation of the fabric presser rod specified by the stop, the fabric presser system is lifted off the stop, as a result of which the pressure on the material to be sewn increases significantly and the entire mass inertia of the fabric presser system comes into effect. As a result, the sewing conditions deteriorate very much.

A stroke regulation is known from the older DE-OS 35 28 295, in which a sensing element acting directly in front of the sewing point is provided, which senses the height difference and influences the control of the lifting drive with the sensed values. In the transition area to a changed fabric thickness, the size of the stroke is adjusted accordingly and then reduced again to the original size. Due to the change in height of the support element carrying the sewing feet, the entire spring forces are also influenced. As the suspension ratios change, the sewing properties also change.

The invention has for its object to provide a height adjustment of the presser system for the presser foot and the upper feed foot which adapts to the respective thickness ratios of the sewing material.

This object is achieved in a sewing machine according to the preamble of claim 1 by the characterizing features. The arrangement according to the invention now results in a automatic adjustment of the height of the carrier system to the respective working height of the sewing material without any significant change in the pressure conditions which basically act on the top feed foot and on the presser foot. The tracking takes place automatically by changing the force ratios on the separately sprung feet. As a result, any manual or motor-controlled tracking can be omitted and an arrangement is achieved in which the contact pressure of the sewing feet only changes slightly for a short time only in the transition area of the change in height of the system, but in the case of equal level, the initial state is immediately restored.

Further advantageous embodiments of the invention result from the subclaims. The measure according to claim 2 enables the reaction forces acting on the sewing feet during the sewing process to be used as a controlled variable. Appropriate training of the controller to avoid excessive control fluctuations is achieved by the application according to claims 3 to 5. The measures according to claims 6 to 9 are used to advantageously adapt the control system to differently designed upper transport systems. Claims 6 and 7 relate to an upper transport system in which the upper transport foot rests on the material during its entire drive phase, while claims 8 and 9 relate to an upper transport drive with an alternating lifting drive for the upper transport foot and the presser foot.

The drawing shows two exemplary embodiments of the invention and various modifications in a sewing machine with top feed. Show it: Fig. 1 is a side view of a sewing machine with a

Top conveyor, partially cut;

Fig. 2 is a diagrammatic representation of the

Drive parts for the top conveyor and its adjustment;

Fig. 3 is an enlarged sectional view of the

Level control for the top feed foot and the presser foot;

Fig. 4 is an enlarged view of the

Transmission elements for the top feed foot, partially cut;

Fig. 5 is a side view, partly in section, of the parts shown in Fig. 4;

Fig. 6 is a side view of the sewing machine with another embodiment of the

Top conveyor;

Fig. 7 is a diagrammatic representation of the

Drive parts for the top feed device and the needle bar and

Fig. 8 is an enlarged sectional view of the

Level control for the second type of upper transport device;

Fig. 9 is an enlarged section of the level control shown in Fig. 8 with a modified version of the guide bushing and

Fig. 10 is a section along the line XX of Fig. 9 and 11 shows a section through a further modified embodiment of the level control according to FIG. 8.

Fig. 1 shows a side view of a sewing machine, in the housing of a presser bar (2) carrying a presser foot (1) and a needle bar (4) mounted in a needle bar carrier (3), the thread-guiding needle (5) of which is shown with a gripper (not shown) works together. To advance the layers of material to be connected to one another, the sewing machine has an upper feed foot (6) which interacts with a lower fabric pusher, not shown.

A main shaft (7) (FIG. 2) which is driven in a known manner and which drives the needle bar (4) via a crank (8) and a link (9) is also mounted in the housing of the sewing machine. The handlebar (9) is mounted on a pin (10) fastened in the crank (8).

On the pin (10) there is also an intermediate member (11) which is connected to a pin (12) which is rotatably mounted in the housing axially to the main shaft (7) and on which an eccentric (13) is fastened. This is encompassed by an eccentric rod (14) which is connected to an angle lever (15) which consists of two lever arms (15a, 15b) which are fastened on a shaft (15c) mounted in an extension of the housing. The lever arm (15b) of the angle lever (15) (Fig. 1) is connected via a link (16) to a pin (17) which is carried by a rocker (18). This is mounted on a pin (19) which is attached to a support element (20). The support element (20) is tauf a piston rod e (21) (Fig. 3) of an actuating piston (22) attached, which is part of a gear connection (23). This contains a follower (27) which consists of a hydraulic cylinder (24), the control piston (22), a control bush (25) and a follower piston (26) which is connected to the presser bar (2).

On the pin (17) a handlebar (28) (Fig. 1) is pivotally mounted, the other end of which is articulated to a support (29) for the upper feed foot (6). The support element (20) also carries a pin (30) on which a telescopic rod (31) is mounted, which is also connected to the carrier (29) via a joint pin (32).

The upper feed foot (6) is driven by a stitch actuator (40) (FIG. 2) which is connected to an eccentric (41) attached to the main shaft (7). The stitch regulator (40) has an adjusting shaft (42) mounted in the housing, which is fixedly connected to a bracket (43), between which its arms e are rotatably supported in a further bracket (44) by means of pins (45). The arms of the bracket (44) are connected by a bolt (46) to which an eccentric rod (47) is articulated. The eccentric (41), which is enclosed by the eccentric rod (47), gives the bolt (46) oscillating movements around the pins (45).

A handlebar (49) engaging on one end on the bolt (46) is articulated on the other end on a lever arm (51) which is attached to one end of an oscillating shaft (52) mounted in the housing parallel to the main shaft (7). A lever arm (53) is connected to the other end of the oscillating shaft (52) and is connected via a link (54) engages a rocker arm (55). This is attached to an oscillating shaft (56) (FIG. 1) mounted in the housing, which carries a further oscillating lever (57) which is connected to the pin (32) of the carrier (29) via a link (58). connected is.

A lever arm (60) is attached to the adjusting shaft (42) (Fig. 2) of the stitch actuator (40) and is connected via a link (61) to a crank (63) attached to an adjusting shaft (62).

A control crank (64) is clamped onto the control shaft (62) mounted in the housing and is connected via an intermediate member (65) and a further control crank (66) to an intermediate shaft (67) mounted in the housing. A lever (68) is attached to this. The lever (68) is connected via a ball pull rod (69) to one end of a rocking lever (70) which can be pivoted about an axis (71) fixed to the housing. The still free end of the rocker arm (70) has a spherical projection (72) and projects into a positioning curve (73) of a lockable adjusting wheel (74) which is arranged on an axle (75) fixed to the housing. The positioning curve (73) in the setting wheel (74) runs in a spiral shape with respect to its axis (75) in such a way that stitch lengths of, for example, 1 to 6 mm can be set on the upper feed foot (6). A spring (76) surrounding the intermediate shaft (67) and fastened at one end in the housing holds the shoulder (72) of the rocking lever (70) in constant contact with one of the side walls of the positioning curve (73).

The adjusting shaft (62) is connected to the lower slide valve, not shown, in a known manner, so that when adjusting the adjusting wheel (74) both the upper feed foot (6) and the lower fabric slide can be adjusted synchronously.

The cylinder (24) (Fig. 1) of the follower (27) is equipped with a collar (80) with a

Screw (81) is fastened in the housing. It has an inner cylinder chamber (82) (Fig. 3) which is connected to a guide bore (83) in the collar (80). The piston rod (21) of the actuating piston (22) is guided in the guide bore (83). This is in the

Cylinder chamber (82) slidably arranged and divides them into an upper and a lower chamber (82a, 82b).

The piston rod (21), which is extended upwards, is guided through a sealing bush (84) which closes off the cylinder chamber (82) and is locked in its axial position by a locking washer (85). The two chambers (82a) are formed by sealing rings (86) which are located in grooves (87) in the sealing sleeve (84) and by a sealing ring (89) inserted in a groove (88) in a pipe extension (80a) of the collar (80) ) and (82b) sealed up and down.

The two chambers (82a) and (82b) are filled with oil, which through a connection piece (90) fastened in the cylinder (24) via a bore (91) projecting into the lowermost part of the lower chamber (82a) from one with the Connection piece (90) connected, not shown supply container is supplied. The connecting piece (90) has a one-way ball valve, so that in the event of oil leakage due to the negative pressure that arises when the adjusting piston (22) goes up, oil is automatically sucked in from the reservoir. An annular groove (92) with a sealing ring (93) is provided in the circumference of the central part of the actuating piston (22). Above and below the annular groove (92), a transverse bore (94a and 94b) is provided in the actuating piston (22), which lie diagonally opposite one another and extends from the circumference of the actuating piston (22) to an inner bore (95) in the piston rod (21) extend. The bores (94a and 94b) are arranged so that they are open towards the lower and the upper flange of the actuating piston (22).

The control bushing (25) mounted in the inner bore (95) of the piston rod (21) has an inner bore (96). In the upper part of the control bushing (25) there is a transverse bore (97) into which a pin (98) protrudes, which is fastened in a lifting piece (99) and also penetrates a slot (100) in the piston rod (21). The cross bore (97) is slightly larger in diameter than the diameter of the pin (98). The lifting piece (99), which has a nose (101) projecting to the rear, is designed in the form of a cap and is slidably mounted on the piston rod (21). It is provided with an annular groove (102) which is open on one side and into which a clamping ring (103) clamped on the piston rod (21) is inserted. The width of the annular groove (102) is larger than the width of the clamping ring (103). A leaf spring (104) arranged in the housing pushes the whole connection system (23) downwards.

In the Steuerbuch se (25) in the area of the stable piston (22) on opposite sides two millings are provided, so that connection chambers (105a, 105b) are formed. From this extends A rectangular opening (106a or 106b) through the wall of the control bushing (25) into the inner bore (96). An annular groove (107) with inserted sealing rings (109) below and above the connecting chambers (105a, 105b) prevent oil from escaping.

In the inner bore (96) of the control bush (25). a control rod (111) is mounted, the central part of which forms the follower piston (26). For this purpose, the part of the control rod (111) above and below the follower piston (26) is reduced in diameter. In its normal position, the follower piston (26) just covers the openings (106a and 106b) in the control bushing (25). Ring grooves (112 and 113) with sealing rings (114 and 115) are provided in the control rod (111) above and below the follower piston (26).

The control rod (111) projects downwards into an axial bore (116) of the presser rod (2) guided in the lower part of the piston rod (21). Both rods (2 and 111) are connected to one another by a pin (110) which is fastened transversely in the presser bar (2) and projects through a slot (117) in the control bar (111). A bore (118) is provided in the presser bar (2), in which a compression spring (119) is received. This is supported against the lower end of the bore (118) and against the control bush (25).

At the lower end of the tube extension (80a) of the collar (80) an annular flange (120) is clamped, in which a bore (121) is incorporated. The end of a rod (123) fastened in a bore (122) in the support element (20) is slidably fitted therein. On the free end of the rod (123) is one on the The presser bar (2) attached to the support lug (2a) is slidably guided. This has a receiving bore (124) for a spring (125) which is supported against the end of the receiving bore (124) and against a reinforcing ring (126) on the rod (123). The rod (123) is closed with a locking ring (127). The two springs (119 and 125) form a measuring element for detecting the forces acting on the sewing feet (1 and 6).

In the neck of the housing (Fig. 1) a shaft (128) is mounted, which is firmly connected to a hand lever (129). On the end of the shaft (128) which projects into the interior of the housing, a cam segment (130) is fastened below the nose (101) of the lifting piece (99).

The telescopic rod (31) arranged between the support element (20) (FIGS. 4 and 5) and the support (29) for the upper transport foot (6) is divided into an upper fork (131) and a lower fork (132). The lower fork (132) is connected to a bolt piece (133) and the upper fork (131) to a socket piece (134), which are pushed into each other and held together by a screw (135) screwed into the bolt piece (133). Between the head of the screw

(135) and the upper fork (131) is a plate spring

(136) and between the 9uchsenstück (134) and the lower fork (132) a divider spring assembly (137) inserted. The preload of the plate spring assembly (137) can be changed by means of a nut (138) which is screwed onto the threaded bushing piece (134). The facility works as follows:

The feed size of the upper feed foot (6) (FIGS. 1 and 2) is adjusted by turning the setting wheel (74), as a result of which the positioning curve (73) rotates the intermediate shaft (67) via the rocker arm (70) accordingly.

The inter mediate shaft (67) adjusts the control shaft (62) via the intermediate link (65) and the

Handlebar (61) and the lever arm (60), the adjusting shaft (42).

This arrangement ensures that the adjustment of the feed of the

Upper feed foot (6) in sync with the feed setting of the lower fabric slide via the

Control shaft (62) is changed.

The movement derived from the eccentric (41) is controlled via the drive connection - eccentric rod (47), bolt (46), handlebar (49), lever arm (51), rocker shaft (52), lever arm (53), handlebar (54), rocker arm ( 55 and 57), handlebar (58), pivot pin (32) and carrier (29) - transferred to the upper feed foot (6), which thereby executes a corresponding feed movement.

Synchronous with the feed movement of the

Upper transport foot (6), the movement which is derived from the intermediate member (11) driven eccentric (13), via the drive connection - eccentric rod (14), angle lever (15), intermediate member (15), pin (17) and lever (28 ) - transferred to the carrier (29) and thus to the top feed foot (6) as a lifting movement. The top feed foot rises and falls in the correct rhythm with its feed movement. When the angle lever (15) swings out (see also FIG. 4), the rocker (18) moves between the positions (A, B) in a work area which is selected such that the movement transmission on the bolts (17) in Area (A) is relatively slow, while area (B) is relatively quick. Thus, the lifting movement transmitted by the link (16) to the carrier (29) is delayed by the rocker (18) in the area between the positions (M 'and A') and accelerated in the area between the positions (M 'and 8') . Accordingly, the upper transport foot (6) moves slowly in the area where it is placed on the material to be sewn, but quickly in the area where it is lifted off, so that bouncing phenomena when it is placed on the material to be sewn are largely avoided.

The leaf spring (104), which has a flat characteristic curve, presses via the piston rod (21), the handlebar (31) and the carrier (29) onto the upper transport foot (6) seated on the material to be sewn. The spring force acting from the leaf spring (104) is z. T. during the pressing phase of the upper transport foot (6) reduced by the reaction force of the plate spring assembly (137).

The upper transport foot (6) is pressed on via the pretension of the plate spring assembly (137) and can be adapted to the desired transport behavior by adjusting the nut (138). The contact spring of the top feed foot (5) is also dampened by the disc spring assembly (137). After placing it on the material to be sewn, the sprung handlebar (31) pushes the carrier (20) to the top, which urc hsichauchd the piston rods (21) wants to push up. The leaf spring (104) acts on the carrier (20) with a predetermined force via the lifting piece (99), the clamping ring (103) and the piston rod (21). From this point, the force is directed to one or both sewing feet (upper feed foot 6 and presser foot 1) depending on the swing position of the rocker (18). The two springs (spring assembly 137 and spring 125) serve as work fields. They are pressed together individually or both together, and press the sewing feet onto the material with a given pressure. The plate spring (136) serves to reduce rebound impacts due to the mass of the upper feed foot (6) at the start of its lifting process. The presser foot (1) itself does not stand out from the sewing material when the sewing machine is in operation.

The telescopic rod (31) shortens during the work process while increasing the spring tension of the plate spring assembly (137) and returns to its original length when the load is released. The plate spring assembly (137) thus takes up the remaining stroke as well as the stroke movement of the lower fabric slide above the needle plate after the upper feed foot (6) has been placed on the sewing material.

The spring (125) has a steep characteristic. It therefore reacts very quickly when the material to be thickened, its change in force is relatively large and therefore also has a favorable effect on the pressure conditions on the adjusting piston (22). Due to its steep spring characteristic, the travel of the spring (125) can only be short. The pressure spring (119) is therefore arranged parallel to it with a flat characteristic curve. Their spring force normally adds to the spring force of the spring (125). Once this, e.g. B. when lifting the two feet (1 and 6) completely relieved by actuating the hand lever (129) and thus becomes ineffective, the compression spring (119) presses the presser bar (2) down and thus guarantees the maintenance of the function of the follower piston (26).

During sewing, an average of the impulsive reaction forces acting on the sewing feet is established. This mean value is transmitted via the carrier (20) to the piston rod (21) or to the presser bar (2). The strongly impulsive reaction forces of the two sewing feet cause rhythmic movement impulses on the connection system (23). You will be greatly dampened by its specific training. This means that the sewing conditions remain relatively rigid and only the sewing feet themselves perform an up and down movement.

Both the component from the spring force of the plate spring assembly (137) and that from the

Combination of the spring forces of the two springs (125 and 119) cause a displacement of the actuating piston (22) into a working position in which a balance between the spring force of the leaf spring (104) and the reaction forces from the springs (119, 125 and 137).

If faults occur due to a change in the material thickness, the reaction forces on the sewing feet change and with it the corresponding forces on the piston rod (21) or on the presser bar (2). If, for example, the upper feed foot (6) sits earlier on the sewing material during the transition to thicker sewing material, the plate spring assembly (137) becomes more strongly connected and then exercises on it Piston rod (21) a higher reaction force. However, due to the closed cylinder chambers (82a, 82b), this remains at rest; only in the upper cylinder chamber (82a) does an increased pressure build up

The reaction force of the presser foot (1) ascending onto the material causes a corresponding shift of the presser rod (2) upwards. When this movement of the presser bar (2) becomes so great that the pin (110) firmly connected to it abuts the upper end of the transverse slot (117), it pushes the control bar (111) with the follower piston (26) upwards. This releases part of the openings (106a and 106b). Oil can now flow from the upper cylinder chamber

(82a) via the bore (94a) in the actuating piston (22), the connection chamber (105a), the two openings (106a and 106b), the connection chamber (105b) and the bore (94b) flow into the lower cylinder chamber (82b) . The adjusting piston (22) can give in to the reaction force from below and also moves upwards until the reaction forces acting on the two rods (2 and 21) have returned to their normal strength and the springs (137, 125 and 119) push the push rod (2) in relation to the piston rod (21) has returned to its normal position. The follower piston (26), which is also displaced, then covers the openings (106a, 106b) again, whereby the two cylinder chambers (82a and 82b) are closed again and the actuating piston (22) is stopped in the new position.

When changing from thicker to thinner material, the reaction forces on the presser bar (2) fall below and below their normal strength is pushed downwards by the springs (119 and 125) until the pin (27) takes the follower piston (26) with it. As a result, the cylinder chambers (82a and 82b) are connected again to one another and exchanged in oil can take place in the reverse direction, with the

The adjusting piston (22) is moved until the conditions have stabilized again.

The lifting movement of the lower fabric slide above the needle plate causes a rhythmic minimal vertical displacement of the fabric presser bar (2) via the sewing feet. The size of this stroke movement is smaller than the length of the lost motion of the pin (110) in the slot (117), so that this idle stroke connection forms a so-called three-point control, which ensures that the gear connection (23) remains in the steady state during normal sewing.

To raise the sewing feet (upper feed foot 6 and presser foot 1), the hand lever (129) is pivoted upwards. The curve segment (130) thereby presses the nose (101) of the lifting piece (99) upwards, which takes the control bushing (25) with it so far that there is between the follower piston (26) and the openings (106a and 106b ) forms a narrow gap. As a result, the cylinder chambers (82a and 82b) are connected to one another in the manner described above and an oil exchange can take place.

When the lifting movement is initiated on the lifting piece (99), this first slides up on the piston rod (21) and takes the control bushing (25) with it via the pin (98) until the play between the lifting piece (99) and the clamping ring (103 ) is overcome. Now there is a gap between the follower piston (26) and the openings (106a and 106b) freely, whereby an oil exchange between the cylinder chambers (82a and 82b) can take place. The lifting piece (99) can thus lift the piston rod (21) and thus the entire associated elements via the clamping ring (103). As soon as the piston rod (21) goes up but the presser rod (2) is still stationary, the follower piston (26) is pulled down relative to the control bush (26) after overcoming the control clearance. Here, the free passage cross section of the openings (106a and 106b) is increased so that the lifting process is as easy as possible.

The sewing feet are lowered by pivoting the hand lever (129) downwards, whereby the cam segment (130) releases the lifting piece (99). The ßlattfeder (104) can now press the control bushing (25) down, whereby the two cylinder chambers (82a and 82b) remain connected to each other, since the presser bar (2) remains in the lower position by the compression spring (119). The actuating piston (22) is then moved downward by the pressure also exerted on it until the connection between the two cylinder chambers (82a and 82b) is separated again. This takes place after the presser foot (1) is placed on the throat plate or the material to be sewn, so that through the resulting reaction force on the presser rod (2) of the follower piston (26) - in the same way as already described - the openings (106a and 106b) closes.

In the embodiment shown in FIGS. 6 to 10, the top transfer device and its connection to the hydraulic controller are opposite greatly modified in the first embodiment. Essentially only the modified version is shown. Elements which correspond to the exemplary embodiment described are provided with the same reference symbols. As far as similar parts are concerned, they are provided with an apostrophe.

In the housing of the sewing machine (FIG. 7), the needle bar support (3 '), which swings around a pivot (150), is mounted. This carries one on the back

Link guide (151) into which a pin (152) of a crank (153) connected to the oscillating shaft (52) protrudes.

As shown in FIG. 6, a presser bar (2 ') which is hollow in its lower end is a

Fixed pin (154) of a carrier (155) which has a bearing eye (156) for receiving a presser foot (1 '). This is pivotally mounted in the bearing eye (156) and has an annular plate (157) which engages around a downward-pointing pin (158) which is fastened to the carrier (155) and extends coaxially to the pin (154). The ring plate (157) is braced by a compression spring (159) arranged on the pin (158) and by a plate spring (161) supported against a locking washer (160) on the end of the pin (158).

With its upper end, the presser bar (2 ') is connected in an articulated manner to a triangular lever (163) via an articulated link (162). An upper transport rod (165), which is displaceably mounted in the needle bar carrier (3), is articulated on this via a further joint plate (164). This has a bore (165) in which a rod part (167) is guided. An upper transport foot (6 ') is attached to its lower end. The stanoic part (167) is with its own Provide elongated hole (168) through which a pin (169), which is fastened transversely in the upper transport rod (165), extends. A pin (170) connected to it in the axial extension of the rod part (167) is guided in an inner shoulder (171) of the bore (166). A spring (172) is mounted on the pin (170) between the rod part (167) and the inner shoulder (171). A second spring (173) is arranged between the inner shoulder (171) and a screw (174) screwed into the upper end of the pin (170). The springs (172 and 173) hold the upper feed foot (6 ') in a predetermined central position

The triangular lever (163) is connected via a hinge pin (175) to an arm (176) which is mounted on a pin (177) fastened in the housing.

The up and down movement of the presser foot (1 ') and the upper transport foot (6') are generated by an eccentric (13 ') (see also Fig. 7) attached to the main shaft (7), which also has an eccentric rod (179) an arm (180a) of an angle lever (180) is connected. This is mounted on a pin (181) fixed to the housing and its other arm (180b) is connected to the triangular lever (163) via a coupling (182) and a bearing pin (183).

The hinge pin (175) is connected to a pin (185) of a transmission rod (186) (FIG. 8) via a pair of plates (184), of which only the foremost plate can be seen. This is part of a transmission connection (23 ') which has a follower regulator (27') consisting of a hydraulic cylinder (24 '), an actuating piston (22') and a follower piston (26), which is connected to the transmission rod (186) connected is.

The cylinder (24 ') is fastened in the housing of the sewing machine with a screw (187). It has an inner cylinder chamber (82) and is with a piece of pipe

(188) connected, the bore (189) is extended to the cylinder chamber (82). In the hole

(189) the piston rod, (21 ') of the actuating piston (22') is guided. This is displaceably arranged in the cylinder chamber (82) and divides it into the upper and the lower chamber (82a, 82b).

The upper part of the bore (189) in the piston rod has an internal thread for screwing in the control bushing (25 '). For this purpose, the upper part is provided with a corresponding external thread. The control bushing (25 ') has an inner bore (191) which merges into a threaded bore (192) in the upper part. A longitudinal slot (193) is also provided in the upper part of the control bushing (25 '). After this

Screwing the control bushing (25 ') into the piston rod (21') and aligning its height and rotational position, the upper part of the control bushing (25 ') is spread by screwing a screw (194) into the threaded bore (192) and with the piston rod (21 ') braced.

In the control bushing (25 ') are in the area of the actuating piston (22'), as in the first

Exemplary embodiment, two connecting chambers (105a, 105b) created by milling are provided, which are supplemented by rectangular openings (106a, 106b).

The control rod (111) projects downward from the control bushing (25 ') into an axial bore (195) in the lower part of the piston rod (21 ') there are transmission rods (186). The two rods (186 and 111) are connected to one another by a pin (196) which is fastened transversely in the transmission rod (186) and projects through a slot (197) in the control rod (111).

At the lower end of the piston rod (21 ') a flange (198) is fastened, on which one end of a compression spring (199) guided on the pipe section (188) rests, the other end of which is supported on the lower part of the cylinder (24') . The transmission rod (186) is firmly connected to a shoulder (200) which is held at a distance from the flange (198) by a plate spring assembly (201). The plate spring assembly (201) and the compression spring (199) hold the actuating piston (22 ') in the stationary state in a center position sprung up and down. A screw (203) is adjustably attached to the attachment (200) by two nuts (202), the shaft of which has a bore (204) in the

Flanged through (198). Between the head of the screw (203) and the flange (198), a plate spring assembly (205) is provided on the shaft. The height of the control bush (25 ') is adjusted so that the follower piston (26) just covers the openings (106a and 106b) in its spring-loaded middle position. The spring characteristic of the plate spring assemblies (201 and 205) can be changed by changing the position of the screw (203) relative to the shoulder (200). These serve as a measuring element for detecting the forces acting on the sewing feet (1 'and 6').

The facility works as follows:

When the main shaft (7) (Fig. 7) rotates, the eccentric rod is attached to the eccentric (13 ') attached to it (179) driven, which, via the angle lever (180) (Fig. 6) and the coupling (182), rotates the triangular lever (163) around the hinge pin (175), which is guided by the arm (176) mounted on the housing.

The torsional vibration of the triangular lever (163) generates the upward and downward movement of the two sewing feet (upper feed foot (6 ') and presser foot (1') and thus also their contact pressure on the material. The contact pressure is determined by the pressure of the springs (159 and 172) of the two sewing feet and the pressure via the gear connection (23 '), as will be explained in more detail later.

The gear connection (23 ') acts with a force determined by the compression spring (199) via the pair of plates (184) on the hinge pin (175) and thus also on the triangular lever (163). From this, the force, depending on the swing position of the triangular lever (163), is applied to one or both sewing feet (upper feed foot 6 'and

Presser foot 1 ') passed. The two springs (159 and 172) serve as working springs. They are pressed together individually or both together, and press the sewing feet onto the material with a given pressure. The springs (161 and 173) are stop springs to avoid rebound impacts during the lifting process of the respective presser foot. When the sewing machine is in operation, an average of the impulsive reaction forces acting on the sewing feet is established. This mean value is transmitted to the transmission rod (186) via the pair of tabs (184). The strongly impulsive reaction forces of the two sewing feet cause rhythmic movement impulses on the gear connection (23 '). They become strong through their specific training subdued. The gear connection (23 ') thus remains relatively rigid with the sewing conditions remaining the same and only the sewing feet themselves perform an up and down movement.

In the event of malfunctions by changing the

Material thickness changes the reaction forces on the sewing feet and thus also on the springs (159, 172). This increases the force on the transmission rod (186) (Fig. 8) accordingly. When changing to thicker sewing material, for example, the springs (159 and 172) of the sewing feet (1 'and 6') are first compressed more, whereby the forces are transmitted to the transmission rod (186) via the movement mechanism. The plate spring assembly (201) arranged between the initially blocked adjusting piston (22 ') and the transmission rod (186) is compressed and thereby indirectly generates a control movement of the transmission rod (186) upwards. Following overcoming the play between it and the pin (196), the follower piston (26) is also pushed upwards and releases part of the openings (106a and 106b). Now oil from the upper cylinder chamber (82a) via the bore (94a) in the actuating piston (22 '), the connection chamber (105a), the two openings (106a and 106b), the

The connection chamber (105b) and the bore (94b) flow into the lower cylinder chamber (22b). The adjusting piston (22 ') can yield to the reaction force from below and also pushes itself upwards until there is an approximate balance of forces between dynamic ones

Linkage forces mean value from below and the static Geσenkraft the compression spring (199) has set. By moving the adjusting piston (22 ") upwards, the openings (106a and 106b) are simultaneously covered by the follower piston (26), the two Cylinder chambers (82a and 82b) are closed again and the actuating piston (22 ') is stopped in the new position.

The plate spring assembly (205) is connected in parallel to the compression spring (199). The two springs (199 and 205) are clamped together with the plate spring assembly (201) via the screw (203). As a result, this spring system can also be subjected to tension, so that the frictional connection and thus also their mutual positive locking in the absence of reaction forces via the sewing feet (1 'and 6'), e.g. B. is not lost in the sudden transition to a lower substance level. This prevents noise and any tendency of the control system to oscillate.

If the pressure force on the combination of the two springs (201 and 205) clamped together increases to such an extent that the spring assembly (205) is completely relieved, a kink arises in the resulting characteristic curve, after which only the spring force of the plate spring assembly (201) is effective. From this bend, the characteristic curve of the spring system becomes flatter, which favors the switching of the tracking movement of the control system when the mass transfer is positive, that is to say increasing. The setting by means of the screw (203) with the two nuts (202) serves to set the power transmission characteristic of the spring system.

In the case of a transition from thicker to thinner material, the reaction forces on the transmission rod (186) fall below their normal strength and this is shifted downwards by the spring assembly (201) until the pin (196) takes the follower piston (26) with it. As a result, the cylinder chambers (82a and 82b) connected again and an oil exchange can take place in the opposite direction, the adjusting piston (22 ') being shifted until the conditions have stabilized.

The lifting movement of the lower fabric slide above the

The throat plate is essentially absorbed by the springs (159 and 172). The possibly still remaining

The stroke effect on the transmission rod (186) is significantly smaller than the length of the lost motion of the pin (196) in the slot (197). This idle stroke connection forms a so-called three-point control, which ensures that the gear connection (23 ') remains in the steady state during normal sewing.

To raise the sewing feet (upper feed foot 1 'and presser foot 6'), the hand lever (128 ') is pivoted upwards. The cam segment (129 ') thereby presses the arm (176) upwards, which also pushes the follower piston (26) upwards via the pair of plates (184) and the transmission rod (186).

As a result, the cylinder chambers (82a and 82b) are connected to one another in the manner described above and an oil exchange can take place. As a result of the pressure simultaneously loading the piston rod (21 ') via the spring assembly (201), the actuating piston (22) moves upwards in the cylinder chamber (82) until it has reached the position determined by the end position of the arm (176) .

The sewing feet are lowered by pivoting the hand lever (128 ') downwards, as a result of which the cam segment (129') releases the arm (176). The through the compression spring (199) formed bias can now push the transmission rod (186) with the follower piston (26) down, whereby the two cylinder chambers (82a and 82b) are connected to each other. The actuating piston (22 ') is then moved downwards by the pressure exerted on the flange (198) by the prestress until the connection between the two cylinder chambers (82a and 82b) is separated again. This takes place after one or both sewing feet have been placed on the needle plate or the material to be sewn, as a result of which the openings (106a and 106b) - in the same way as already described - are generated via the reaction force that arises on the transmission rod (186) of the follower pistons (26). closes.

FIG. 9 shows a shape of the actuating piston and the control bushing which is modified compared to the configuration according to FIG. 8, in order to achieve a fine adjustment of the initial position of the hydraulic regulator. The control piston (22 ") of the controller (27") is provided with an annular groove (208) in which a sealing ring (209) is inserted. The actuating piston (22 ") is chamfered above and below the annular groove (208), so that inclined surfaces (210 and 211) are formed, in which four upper and four lower bores (212 and 213) offset by 90 ° are provided, which extend outwards from the bore (1.89) in the actuating piston (22 "). The bore (189) has an annular groove (214 and 215) in the area of the bores (212 and 213).

The control book (25 ") consists of a socket part (216) and a socket part (217) which are pushed into one another and glued to one another. The socket part (217) contains two opposing milled portions (218a and 218b) which cover the Cover the follower piston (26) straight in its middle position. The socket part (216) has two diagonally opposed and mutually vertically offset milled portions (219a and 219b) such that one milled portion (219a) in the area of the annular groove (214) and the other milled area (219b) in the area of the annular groove (215) is arranged. In addition, the milling (219a) is opposite an upper part of the milling (218a) and the notch (219b) is opposite a lower part of the milling (218b). In this way, the average height of the follower piston (25) can be finely adjusted by simply turning the control bushing (25 ").

When the follower piston (26) is displaced in the manner described in the previous embodiment, oil can be exchanged between the upper cylinder chamber (32a) and the lower cylinder chamber (82b). The oil flow takes place through the bores (212) in the actuating piston (22 "), the annular groove (214), the milling

(219a), the milling (218a), the free interior of the bore (191 '), the milling (218b), the milling (219b), the annular groove (215) and the bore (213) until the follower piston (26) the two millings (218a and 218b) are closed again.

The modification according to FIG. 11 differs from that. Arrangement according to Fig. 8 by an additional compression spring (210) between the control bushing (25 ') and de: transmission rod (186) and by another

Spring connection in the lower part of the follower (27 '). For this purpose, a spring housing (211) is clamped on the piston rod (21 '), which receives a preloaded plate spring assembly (212). This is supported on the one hand against the spring housing (211) and on the other hand against a bushing (213) guided on the transmission rod (186) or a shoulder (214) of the transmission rod (186). A locking ring (215) inserted in a groove in the spring housing (211) secures the position of the bushing (213).

During the normal sewing process, the transmission rod (186) remains immobile. The pressure of the reaction forces acting on the sewing feet (1 'and 6') is exerted on the shoulder (214) of the transmission rod (213)

Disc spring assembly (212) and is picked up by this. Only when these forces acting from below exceed the pretension of the plate spring assembly (212) can the transmission rod (186) move upwards and open the inflow to the two cylinder chambers (82a and 82b) in the manner described above in order to adjust the middle height of the sewing feet ( 1 'and 6').

If the reaction forces fall below the pretension of the plate spring assembly (212), this rests on the bush (213) and thus loses its effect on the transmission rod (186). The shifting of the transmission rod (186) downwards and the initiation of the control process now takes place exclusively through the relatively soft compression spring (210).

The working range of the controller (27 ') lies during normal sewing within the pretension of the plate spring assembly (212), so that the control function of the controller (27') does not start in this area. In the upward mass transfer there is an increased back pressure by the two springs (210 and 212), while in the downward mass transfer by the spring (210) one relatively soft sewing guidance of the sewing feet (1 'and 6') takes place.

Claims

1. Sewing machine with an upper transport device having an upper transport foot and with a presser foot

Presser device, with a lifting and a sliding drive for the upper feed foot, with a gear connection arranged between the upper feed foot and the presser foot, the height of which can be adjusted by an adjusting means, and with a spring arranged between the gear connection and the housing of the sewing machine, characterized in that the gear connection (23, 23 ') for automatically adjusting its height relative to the housing contains a follower acting in the vertical direction.

2. Sewing machine according to claim 1, characterized in that the follower is a hydraulic controller (27, 27 ') which is attached to the housing of the sewing machine and contains an actuating piston (22, 22') and a follower piston (26) which a as

Fader means (119, 125 or 201, 205 or 210, 212) formed measuring member are clamped together.

3. Sewing machine according to claim 2, characterized in that the gear connection between the actuating piston (22, 22 ') and the follower piston (26) includes a three-position switch. Sewing machine according to claim 3, characterized in that the three-point switch is designed as an idle stroke connection (110, 117 or 196, 197).

Sewing machine according to one of claims 2 or 3, characterized in that the follower piston (26) is displaceable in an inner bore (96 or 191 or 191 ') of a control bush (25 or 22 "or 22") connected to the adjusting piston (22 or 25 or 216, 217) and in their normal position predetermined by the measuring element openings (106a, 106b or 218a, 218b) to an upper and a lower cylinder chamber (82a, 82b) of the hydraulic regulator (27 or 27 'or 27 ") covers.

Sewing machine according to claim 4 or 5, characterized in that the adjusting piston (22) is connected to the upper transport foot (6) via a spring connection (telescopic rod 31) and the follower piston (26) is connected to the presser foot (1) via the idle stroke connection (110, 117) is.

Sewing machine according to claim 6, characterized in that the connection between the upper feed foot (6) and the controller (27) is designed as a telescopic connection.

Sewing machine claim 4 or 5, characterized in that the follower piston (26) is connected both to the upper feed foot (6 ') and to the presser foot (1') via the idle stroke connection (195, 197). Sewing machine according to claim 8, characterized in that the connection between the upper feed foot (6 ') and between the presser foot (1') and the controller (27 ') is designed as a double-acting spring arrangement (159, 161 and 172, 173) is.