DE20203790U1 - Toggle clamp - Google Patents

Description

Knee lever clamping device

Description Genus

The invention relates to a toggle lever clamping device, in particular for use in body construction in the automotive industry.

State of the art

DE 198 24 579 C1 describes a toggle lever clamping device, in particular for use in the bodywork construction of the automotive industry, with a clamping head and a cylinder connected to it in axial extension, in which a piston, which is to be pressurized alternately on both sides by pressure medium, is guided in a longitudinally displaceable, torsion-proof and sealing manner, which piston rod passes through the cylinder and the clamping head, wherein at the free end of the piston rod within the housing of the clamping head there is arranged a toggle lever joint arrangement to which a clamping arm is assigned, wherein the piston

the cylinder is divided into a cylinder return stroke chamber and a cylinder clamping stroke chamber, and the cylinder clamping stroke chamber is sealed at the front end by a cover, a housing wall or the like, with end position sensing devices for the piston in the form of contactless, for example inductive sensors or the like, with a brake piston or a stop piston which is assigned to the piston and arranged coaxially to it in the same cylinder as the piston, with an adjusting device for the brake piston or the stop piston arranged in the cylinder base, with which the latter can be continuously adjusted and locked axially in both directions from the outside of the cylinder base without dismantling the toggle lever clamping device for the simultaneous and joint changing and/or setting of the opening angle of a clamping arm and the end position sensing, wherein a sensor of the end position sensing device is assigned to the brake or stop piston. The adjusting device is designed as a clamping screw arranged coaxially to the brake or stop piston, which is arranged in a bore in the cylinder base and locked by a lock nut. The adjustment device can also be designed as a linear motor, air motor, hydraulic motor, electric spindle motor or as a piston-cylinder unit that is alternately pressurized on both sides. The brake piston and thus the opening angle, the end position sensing and, if necessary, the end position damping can be adjusted in stages - intermittently - in the axial direction.

With this toggle lever clamping device, the cylinder end position, the opening angle of a clamping arm, the end position sensing and, if applicable, end position damping can be set simultaneously and together using an adjusting element. If, for example, working conditions change, only the adjustment needs to be made using the adjusting element, without dismantling the toggle lever clamping device and its cylinder. This means that the parameters that match one another, i.e. cylinder end position, opening angle of the clamping arm, end position sensing and, if applicable, end position damping, can be set together and simultaneously and locked in the desired position. This can also be done during operation if necessary. This is an advantage if, for example, it becomes apparent that tolerances are not being adhered to exactly or the contours of the parts to be clamped have changed. In this case, the adjusting element can be operated from the outside of the toggle lever clamping device in order to make the desired settings, so to speak with one hand. This is an advantage that should not be underestimated, as it means that there are no downtimes in the automotive industry's production lines, which would otherwise be associated with high costs for set-up times, etc. In addition, the adjusting element enables the desired sensitive adjustment under operating conditions. Since the adjusting element can be arranged in a non-obstructive place, for example on the cylinder base, the outer contour of the toggle lever clamping device is not adversely affected, so that its all-round mounting option \/on four sides is retained. No

Openings can be provided on the cylinder, on the clamping head or the like in order to arrange sensors, for example. Rather, with this design it is possible to move all electrical cables, sensors and damping elements into the toggle lever clamping device, for example into the cylinder and/or the clamping head.

As can be seen, in all versions, sensors and contacts as well as electrical cables are protected in the toggle lever clamping device. However, it is particularly advantageous that the cylinder end detection, opening angle, end position detection and, if applicable, end position damping can be changed and locked simultaneously and in the same direction using a simple tool, i.e. very quickly and with a built-in toggle lever clamping device, sensitively.

From DE 298 11 331 U1, a device for holding, positioning or clamping, in particular for holding, positioning or clamping body parts, is already known with a housing in which a device that is translationally movable under the action of an actuating device is arranged, and a clamping and holding arm, wherein the movable device and the rod of the actuating device are connected to one another by means of a length-adjustable device. The rod of the actuating device has a threaded bore, wherein the movable device is provided with a connecting element,

which has an external thread at one end, in order to achieve a length adjustment by mutual screwing of the threaded hole in the rod with the threaded end of the connecting element. The connecting element is connected to the movable device in a rotationally fixed manner. The connecting element has a design which cooperates with an end position query device for the clamping and holding position, wherein the connecting element is provided with a flag, the position of which can be determined by a suitable end position query device connected to the housing of the device. The rod of the actuating device is connected to the actuating device in a rotationally fixed manner, for example by being fastened to an elongated or rectangular piston. The rod and the actuating device have a design which cooperates with an end position query device for determining the release or opening position. A flag is fastened to the rod, the position of which can be determined by a suitable end position query device connected to the housing of the device. At least one end position sensing device, which is connected to the housing of the device, is a contactless, preferably inductive end position sensing unit. The end position sensing devices are arranged in the same end position sensing module. This design is intended to solve the problem of remedying the disadvantages of a prior art mentioned in the document, with which it should be possible to adjust the paths and angles without dismantling and without rebuilding the device.

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ensuring good adjustment accuracy when holding and releasing the parts to be held. To perform the adjustment, the piston-cylinder unit must be detached from the clamping head by unscrewing fastening screws, after which the piston-cylinder unit as a whole can be rotated with the piston rod about the axis of its external thread. This should achieve a gradual adjustment of one angular degree at the clamping and holding degree for each half revolution of the piston-cylinder unit about the screw axis. This should make it possible to adjust the clamping and holding position as well as the opening and release position without any intervention other than screwing the piston-cylinder unit as a whole around the threaded rod. This should make it possible to use the same device for a wide, usable angular and positioning range.

The patent application 101 36 057.6-15, which was not previously published and is attributed to the applicant, describes a toggle lever clamping device, in particular for use in the bodywork construction of the automotive industry, with a clamping head and a drive connected to it in the axial direction - a piston-cylinder unit or a linear motor or an electric motor which is to be pressurized alternately on both sides by pressure medium - which drives a rod back and forth in its longitudinal axis direction, which is coupled to a toggle lever joint arrangement via a gear element such as a handlebar, fork head or the like, wherein the

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Knee lever joint arrangement drives a clamping arm pivotably back and forth, the rod being connected to the gear element via a thread axially adjustable in both directions,

a) the rod, which has an external thread - metric thread, Whitworth thread, trapezoidal thread - at its end section facing the toggle joint arrangement, is screwed into a bore in the gear element which has an internal thread;

b) the rod can be rotated about its longitudinal axis in both directions through a hole in a base cover at the end facing away from the clamping head for the purpose of its axial adjustment;

c) a guide plate is arranged on the rod, which engages with diametrically opposed projections in guide grooves of the clamping head, which guide the guide rollers of a bolt in the longitudinal direction of the clamping head;

d) at the end section facing the drive, a free space is arranged, the extents of which measured transversely to the longitudinal axis of the rod are considerably larger than the transverse dimensions of the guide plate measured in this direction.

Furthermore, this unpublished patent application describes a toggle lever clamping device with a clamping head and a drive designed as an electric motor which is connected to it in the axial direction and which drives a rod designed as a ball screw back and forth in its longitudinal axis direction, which is coupled to a toggle lever joint arrangement via a gear element such as a handlebar, fork head or the like, wherein the toggle lever joint arrangement drives a clamping arm so that it can pivot back and forth, wherein the ball screw is connected to the gear element so that its length can be adjusted in both directions, wherein

a) the ball screw meshes with a screw nut arranged in the stator so as to be immovable, and the ball screw is arranged at its end facing away from the clamping head so as to be adjustable in both directions by turning for the purpose of pivoting the clamping arm, if necessary after removing a base cover;

b) a guide plate is arranged on the ball screw, which engages with diametrically opposed projections in guide grooves of the clamping head and guides the guide rollers of a bolt in the longitudinal axis direction of the clamping head;

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c) a free space is arranged at the end section facing the drive, the extent of which measured transversely to the longitudinal axis of the ball screw is considerably larger than the transverse dimensions of the guide plate measured in this direction.

Task

The invention is based on the object of designing a toggle lever clamping device in such a way that the adjustment of the opening angle of the clamping arm can be accomplished with robust means.

Solution

The problem is solved by the features set out in claim 1 or 2.

Some advantages

In the solution according to claim 1, grids, recesses, blind holes, knurls or the like can be provided in the factory in the longitudinal axis direction of the clamping head, to which an opening angle of the clamping arm corresponds in each case according to the stroke. On the outer housing of the

A suitable scale can be provided on the clamping head so that the operator can adjust the swivel angle of the clamping arm accordingly by positively connecting the length-adjustable parts in question. This means that there is no longer any risk of the length-adjustable parts being incorrectly or incorrectly adjusted to one another. In fact, the corresponding angles can be precisely specified in the factory in this way, since each angle corresponds to a corresponding positive connection on the length-adjustable parts.

In the solution according to the secondary claim according to claim 2, the adjustment is carried out by a stroke limiting part which is arranged on the drive rod designed as a threaded spindle so that it can be adjusted and locked in the axial direction. This rod penetrates more or less deeply into a hollow shaft of a hollow shaft motor designed as an electric motor, as is basically described in DE 36 13 644 C2 of the applicant.

Further inventive embodiments

Further inventive embodiments are described in claims 3 to 7 .

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In the embodiment according to claim 3, a toothed rack is assigned to the mutually length-adjustable parts of the toggle lever joint arrangement on the one hand and the piston rod on the other, so that the swivel angle of the clamping arm can be changed by appropriately locking a counterpart over the constant stroke of the piston-cylinder unit, which is alternately acted upon on both sides by pressure medium pressure, in particular by air pressure. Fine adjustment is not necessary here, since the respective swivel angle is predetermined by the positive connection between the assigned teeth.

According to claim 4, the positive connection can also be made by means of a snap fastener, while in claim 5 one of the length-adjustable parts is provided with groove-shaped recesses into which a corresponding counter bearing of another length-adjustable part, for example the piston rod, engages, thereby enabling a positive connection between the piston rod and the drive rod.

In claim 6, a further advantageous embodiment is described, in which a stroke limiting part can be adjusted in the axial direction of the drive rod, in this case a threaded spindle, and engages with the drive rod or threaded spindle in a force-fitting or form-fitting manner, for example via teeth or threaded sections, in the corresponding recesses of the drive rod,

In this embodiment, a too hard impact is prevented, at least in the open position, by the provision of an end position damper. Such an end position damper can be an industrial shock absorber or, preferably and simply, made of a polymer plastic that has rubber-like properties and is resistant to the water and/or vapors normally encountered in industry. This end position damper can also be installed in the space delimited by the clamping head on the front side facing the linear drive and is practically maintenance-free.

Another very advantageous embodiment is described in claim 7. In this embodiment, the piston rod is connected to the toggle joint arrangement by a clamping connection, e.g. a clamp or the like, which is fixed in terms of gearing but detachable and adjustable.

The invention is illustrated - partly schematically - in the drawing. It shows:

Fig. 1 a toggle lever clamping device, partly in longitudinal section, partly in

Opinion;

Fig. 2 is a section along the line II - II of Fig. 1;

Fig. 3 shows another embodiment of the invention, partly in longitudinal section,

partly in the view;

Fig. 4 is a section along the line III - III of Fig. 3;

Fig. 5 another embodiment, also partly in longitudinal section, partly

in the view;

Fig. 6 is a section along the line V - V of Fig. 5 and

Fig. 7 shows another embodiment of the invention, also partly in

Longitudinal section, partly in elevation.

In the drawing, the reference number 1 designates a clamping head which is rectangular in cross-section and consists of two housing parts 1a and 1b which lie flat on top of one another on their adjacent sides. The housing parts 1a, 1b can be designed as housing halves and enclose a space 2 in which a toggle joint arrangement 3 is arranged in a protected manner. Via the toggle joint arrangement 3, a clamping arm 4 is powered in the direction A or B about a pivot axis 5 fixed to the housing by a piston-cylinder unit 6 which is alternately acted upon on both sides by pressure medium pressure, in particular by air pressure. The pivot axis 5 fixed to the housing is circular in cross-section on its longitudinal section, on which it is pivotally mounted (not shown), and can also be mounted here with low friction in rolling bearings, in particular needle bearings, which run smoothly.

The toggle joint arrangement 3 has one or more joint brackets 35, which each have holes at their opposite end areas through which the pivot axes 7 and 8 extend. The joint brackets 35 are pivotally coupled to the clamping arm 4 via the pivot axis 8, while the pivot axis 7 is gear-coupled to a drive rod 10 via a coupling part 9 designed, for example, as a fork head. The drive rod 10 can be designed in one piece with the coupling part 9 in terms of function or material.

In all embodiments shown, the clamping head 1 is equipped with threaded blind holes (not shown) on all four sides, so that the toggle lever clamping device can be attached to one of the four sides if required, even from the rear.

On the back, the clamping head 1 is provided with a longitudinal slot 12 extending in the direction of the longitudinal axis 11, the longitudinal axis of which runs parallel to the longitudinal axis 11 and into which a holder 13 designed as a cassette is inserted, which seals the longitudinal slot 12 from the outside. For this purpose, the cassette can be L-shaped in cross-section or designed in some other way, with one leg sealing the longitudinal slot 12, while sensors 14 and 15 that can be adjusted relative to one another are arranged on the other longitudinal slot and are dampened by a switching flag 16. The switching flag 16 is in the

In the embodiments shown, the clamping arm 4 is connected to the coupling part 9 in one piece but in an exchangeable manner, but can also be coupled directly to the drive rod 10. The position of the clamping arm 4 can be detected by the sensors 14 and 15 on the one hand and the switching flag 16 and the switching flag 42 on the other hand and the respective position can be visually and/or acoustically indicated to a more distant location, for example to a monitor (not shown). The switching flag 16 detects the clamping position of the clamping arm 4, while the switching flag 42 detects the open position of the clamping arm 4. The indication is made via electrical lines (not shown) which are connected to a plug 17, which in turn is connected to the sensors 14 and 15 by electrical lines (also not shown).

In the embodiments according to Figs. 1 to 6, the drive rod 10 engages in a blind bore 18 in a longitudinally displaceable and lockable manner.

In the embodiment according to Fig. 1 and 2, the drive rod 10 is equipped at least on one side with a toothing 21, which has several teeth running parallel to one another and with their longitudinal axes orthogonal to the longitudinal axis 11 in the manner of a rack or the like. A locking part 19 corresponds to the toothing 21, which is also equipped with a toothing that can engage in a form-fitting manner in the toothing 21 of the drive rod 10. The locking part 19 can be connected in a form-fitting manner to the drive rod 10 by a fastening element 20, in particular a screw. It is also possible to connect the fastening element 20 in the manner of a

The catch is mounted against the restoring force of a compression spring (not shown) so that after the catch in question is lifted, the drive rod 10 can be adjusted relative to the blind bore 18. The blind bore 18 is arranged in a piston rod 22 which is connected to a piston 23 which divides a cylinder chamber 24 into two individual cylinders sealed against each other by seals 25, to which pressure medium, in particular compressed air, can be supplied in a controlled manner alternately through a channel 26 or 27. The control system can be incorporated into a sequence control system of a production line (not shown).

The piston rod 22 is sealed in a cover 28 and guided for longitudinal displacement.

By loosening the screw or screws 20, the positive connection between the teeth of the locking part 19 and the teeth 21 of the drive rod 10 can be removed and the latter can then be inserted more or less far into the blind bore 18 in the desired manner and then fastened again, whereby the pivoting angle of the clamping arm 4 in the X or Y direction can be changed.

In the embodiment according to Fig. 3 and 4, the piston rod 22 is provided with a collar-shaped thickening 29 at its end, which is provided on its upper side (in the

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Seen from the plane of the drawing) has a bore 30 with its longitudinal axis orthogonal to the longitudinal axis 11, into which a grub screw or the like 31 can be screwed more or less far, which has a conical end which, if required, engages in a blind hole-like depression 32 adapted to the end of the grub screw or the like, the longitudinal axis of which also runs orthogonal to the longitudinal axis 11. Several such blind hole-like depressions 32 are arranged next to one another at a distance and parallel with their longitudinal axes in the longitudinal axis direction of the drive rod 10 and thus the piston rod 22, so that after loosening and moving the drive rod 10 relative to the piston rod 22 and screwing in the grub screw 31 again, the pivot angle of the clamping arm 4 can be changed intermittently or, in practice, sensitively.

In the embodiment according to Figs. 5 and 6, the same reference numerals have also been used for parts with the same function. This embodiment differs from the previously described in that the drive rod 10 is provided with numerous recesses, grooves or the like 33 arranged coaxially to the piston rod 22 in the longitudinal axis direction, one behind the other in which a screw 34 or the like with its adapted dome engages in a form-fitting manner if required. By loosening the screw 34 or the like, the drive rod 10 can be moved in the axial direction relative to the piston rod 22 and by fastening the screw 34 or the like

can also be positively connected to one another, whereby the pivoting angle of the clamping arm 4 can also be changed.

In the embodiment according to Fig. 7, the same reference numerals have been used for parts with the same function. This embodiment differs from the previously described embodiments in that, instead of a piston-cylinder unit, an electric motor 36 is flanged coaxially to the drive rod 10 by means of several replaceable screws (not shown). The hollow shaft motor drives the drive rod 10, which is designed as a threaded spindle, in the X or Y direction, whereby the latter penetrates more or less deeply into a hollow shaft 37.

The reference number 38 designates a stationary nut which is driven by the hollow shaft 37 of the electric motor and thereby drives the threaded spindle 10 in the direction X or Y, whereby the swivel arm is swiveled in the direction A or B into its housing-fixed axis 5.

A stroke limiting part 39 is arranged on the threaded spindle 10 and can be arranged detachably on the spindle 10 by means of at least one screw 40 or the like. For this purpose, the stroke limiting part 39 can consist of two or more jaws which are clamped onto the screw spindle 10 by means of several screws. The jaws can be provided on their inside with the

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The swivel angle of the clamping arm 4 can be changed accordingly by axially moving the stroke limiting part 39 and locking it again.

At 41, an end position damper is arranged, which can consist of a polymer plastic with elastic properties or the like and which has a central opening through which the threaded spindle 10 extends.

The features described in the claims and in the description as well as those evident from the drawings may be essential for the realisation of the innovation both individually and in any combination.

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List of reference symbols

1 Clamping head 1a Housing part 1b I) 2 Space 3 Knee joint arrangement 4 Clamping arm 5 Swivel axis, housing-fixed 6 Piston-cylinder unit 7 Swivel axis

9 Coupling part

10 Drive rod, threaded spindle

11 Longitudinal axis

12 Longitudinal slot

13 Cassette, holder

14 Sensor, micro switch, inductive switch, clamping position

15 &ldquor; , &ldquor;;&ldquor; open position

16 Switch flag

17 plugs

18 Blind hole

19 Locking part

20 Fastener, screw

21 Gearing

22 Piston rod

23 pistons

24 Cylinder chamber 25 poetry 26 channel 27 11 28 Lid 29 Thickening, collar-shaped 30 drilling 31 grub screw, screw, fastening part 32 thickening 33 recess, groove 34 screw 35 Joint strap 36 Electric motor

37 Hollow shaft

38 Nut, spindle nut, &zgr;. B. Trapezoidal spindle nut

39 Stroke limiting part

40 Screw

41 End position damper

42 Switch flag, open position

A Swivel direction of the clamping arm 4

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X Stroke direction

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bibliography

DE-AS 22 22 686 DE-AS 29 26 258 DE-OS 24 31 706 DE-OS 25 19 251 DE-OS 25 55 207 DE-OS 27 18 639 DE-OS 41 11 430 DE-OS 42 42 601 DE- PS 24 48 028 DE-PS 28 28 344 DE-PS 30 22 376 DE-PS 34 03 961 DE-PS 36 13 644 DE-PS 196 16 441 DE-PS 198 24 579 unpublished German patent application 101 36 057.6-15

DE-U-87 14 390 DE-U-89 08 288.5 DE-U-90 05 183.1 DE-U-90 16 781.3 DE-U-91 04 532.0 DE-U-91 05 755.8 DE-U-92 15 151.5 DE -U-93 11 132.0 DE-U-295 04 267 DE-U-295 13 586.7 DE-U-295 19 232.1 DE-U-297 00 981 DE-U-297 18 644.2 DE-U-298 11 331

EP-A-O 005 407 EP-A-O 080 565 EP-A-O 256 208 EP-A-O 313 767 EP-A-O 317 924 EP-A-O 359 073 EP-A-O 417 024

EP-A-O 433 601 EP-A-O 595 074 EP-A-0 636 449 EP-A-O 648 941 EP-A-O 695 603 EP-A-O 778 107 EP-A-O 803 331 EP-A-O 962 285

WO-A-92/08899

GB-A-1 413 751 GB-A-495 563

FR-A-2 427 179 FR-A-2 431 625 FR-A-2 618 718

JP-AS 9548/73

US HP 2,980,387 US HP 2,983,256 US HP 2,985,140 US HP 3,180,236 US HP 3,371,953 US HP 3,482,831 US HP 3,815,480 US HP 3,961,559 US HP 3,994,539 US HP 4 .240,620 US HP 4,424,737 US HP 4,429,715 US HP 4,664,364 US HP 4,700,611 US HP 4,905,973 US HP 5,072,652 US HP 5,171,001 US HP 5,201,838 US HP 6,220,588 US-08/759 518

&bull; it. * » » S · i 9

Catalogue "Clamping technology" of the company DE-STA-CO, Frankfurt 1972/1973, p.72/73

Brochure from ISI Anlagen- und Komponenten Vertriebs GmbH - "New force in gripper technology. Only from ISI."

“Quick Change Gripper Head Mounts” from LS.L Manufacturing Inc.

Brochure from ISI Manufacturing Inc. "Other ISI Products", especially "The Grip-Lok System: Proven gripper technology"

Brochures KG84A32101, KG84A32102, KG84A32103, KG84A32104 of the company DE-STA-CO Metallerzeugnisse GmbH concerning "Curve clamp grippers, single clamp grippers, double clamp grippers"

Brochure of the company Sommer Automatic GmbH "Knee lever gripper GK 20, GK 25"

Brochure of the company Fritz Schunk GmbH "Knee lever gripper, type PKG, pneumatic"

Brochure sheet of the company Fritz Schunk GmbH "15.2" and "15.3"

Claims (7)

1. Knee lever clamping device, in particular for use in bodywork construction in the automotive industry, with a housing-like clamping head ( 1 ) which accommodates a knee lever joint arrangement ( 3 ) in a space ( 2 ), a linear drive ( 6 , 36 ) connected in the axial direction of the clamping head ( 1 ) for the stroke-movable driving of a drive rod, threaded spindle, piston rod or the like ( 10 ) in opposite directions (X or Y), wherein the drive rod ( 10 ) or the like is gear-connected to the knee lever joint arrangement ( 3 ), a clamping arm ( 4 ) which is pivotable (A or B) from the knee lever joint arrangement (3) about an axis ( 5 ) fixed to the housing, wherein the knee lever joint arrangement ( 3 ) can be coupled to the drive rod or the like in a length-adjustable manner, characterized in that the coupling of the drive rod ( 10 ) assigned to the knee lever joint arrangement is arranged in a longitudinal direction (A) of the knee lever joint arrangement. 10 ) can be produced by a positive or non-positive connection with the piston rod ( 22 ) of the linear motor designed as a piston-cylinder unit to be acted upon alternately on both sides by pressure medium pressure, in particular by air pressure. 2. Knee lever clamping device, in particular for use in bodywork construction in the automotive industry, with a housing-like clamping head ( 1 ) which accommodates a knee lever joint arrangement ( 3 ) in a space ( 2 ), a linear drive ( 6 , 36 ) connected in the axial direction of the clamping head ( 1 ) for the stroke-movable driving of a drive rod, threaded spindle, piston rod or the like ( 10 ) in opposite directions (X or Y), wherein the drive rod ( 10 ) or the like is gear-connected to the knee lever joint arrangement ( 3 ), a clamping arm ( 4 ) which is pivotable (A or B) from the knee lever joint arrangement ( 3 ) about an axis ( 5 ) fixed to the housing, wherein the knee lever joint arrangement ( 3 ) can be coupled to the drive rod or the like in a length-adjustable manner, with an electric motor ( 36 ) designed as a hollow shaft motor for driving a drive rod ( 10 ) designed as a threaded spindle, characterized in that the threaded spindle ( 10 ) is assigned a stroke limiting part ( 39 ) which is adjustable in its longitudinal axis direction and can be locked, for example, in a form-fitting or force-fitting manner. 3. Toggle lever clamping device according to claim 1, characterized in that the drive rod ( 10 ) extends into a bore of the piston rod ( 22 ) and that the drive rod ( 10 ) is provided with a plurality of recesses, teeth or the like spaced apart in the direction of its longitudinal axis in the manner of a rack, into which a coupling part, in particular a screw with its tip or the like, alternately engages releasably for the purpose of coupling the drive rod ( 10 ) to the piston rod ( 22 ). 4. Knee lever clamping device according to claim 3, characterized in that the coupling part is designed as a snap catch which is mounted on the piston rod against the restoring force of a spring. 5. Toggle lever clamping device according to claim 1 or one of claims 3 and 4, characterized in that the drive rod ( 10 ) has a plurality of groove-shaped depressions, grooves or the like into which the coupling part engages or acts in a positive or non-positive manner. 6. Toggle lever clamping device according to claim 2, characterized in that an end position damper ( 41 ) for limiting the stroke is assigned to the stroke limiting part ( 39 ) at least on one side at the end section of the threaded spindle ( 10 ) assigned to the linear drive ( 36 ). 7. Knee lever clamping device according to claim 1 or 2, characterized in that the piston rod ( 22 ) is coupled - directly or indirectly - to the knee lever joint arrangement ( 3 ) or a coupling part ( 9 ) connected thereto by a clamping connection, for example a clamping clip.