EP2642094B1 - Switchable swing arm - Google Patents

Description

The invention relates to a switchable rocker arm for a valve train of an internal combustion engine.

Switchable rocker arms are usually used to realize a variable valve lift for gas exchange valves of an internal combustion engine.

EP 1 785 595 A1 describes a switchable rocker arm or drag lever for a valve train of an internal combustion engine. This switchable oscillating lever has an inner and an outer lever enclosing this with its arms, wherein the two levers are pivotable relative to each other on a common axis and selectively connectable to each other via a slide movable transversely to this axis or along the two levers. The outer lever has on each arm a sliding surface providing a thrust surface for a high-lift cam. The inner lever has a rolling bearing roller for a small or 0-Hubnocken providing roller bearing. The inner lever also has at one end at one end a system for a gas exchange valve and at the other end a complementary surface for storage on a pivot point for the entire oscillating lever providing head of a support element.

Furthermore are already in the GB 2 199 894 , as well as in the EP 0 267 696 A1 Valve drives described with switchable rocker arms, in this one hand, the two-sided flanking a second lever by receiving this second lever between the two arm portions of a first lever is shown, and on the other hand to be reduced in these friction losses by using rollers.

On this basis, the object of the invention is to provide a switchable rocker arm which causes lower friction losses in the valve train.

This is achieved with a switchable rocker arm according to claim 1. Further developments of the invention are defined in the dependent claims.

According to the invention, a switchable oscillating lever for a valve train of an internal combustion engine comprises: a first lever part with a first pivot bearing, via which the first lever part about a first axis of rotation is pivotally supported on a housing of the internal combustion engine, and at least one roller rotatably mounted on the first lever part is mounted and has a lateral surface for against it starting a first cam of the valve gear for generating a pivoting movement of the first lever part about the first axis of rotation; a second lever part which is arranged adjacent to the first lever part and which has a second pivot bearing, via which the second lever part is pivotable about a parallel to the first axis of rotation extending second axis of rotation on the housing of the internal combustion engine, and has a roller rotatably mounted on the second lever part and which has a circumferential surface for, however, start-up of a second cam of the valve drive for generating a pivoting movement of the second lever part about the second axis of rotation; and a clutch device having a slider assembly that is controllably movable for shifting, such that the first and second lever members are selectively engageable with each other via the slider assembly with respect to their respective pivotal movements and can be decoupled from each other; wherein on one of the first and the second lever pulley an actuating portion for actuating a gas exchange valve of the internal combustion engine is provided.

Characterized in that on each of the two lever parts, a roller is provided to start against a cam of the valve train, caused by the rocker arm in the valve train friction losses are significantly reduced.

According to the invention, the first axis of rotation and the second axis of rotation are aligned with each other or are coincident with each other.

The fact that each of the two lever parts has its own pivot bearing for pivotal support on the housing of the internal combustion engine and their respective axes of rotation are aligned, a simpler result in the connection of the two lever parts can be realized in a common storage. In particular, space and cost saving several switchable rocker arm can be stored and pre-assembled together with several non-switchable rocker arms on a common axis.

According to the invention, the first pivot bearing has a first through passage extending through the first lever part, into which a first axis section supported on the housing of the internal combustion engine can be fitted, so that the first lever part is pivotable about the first axis section for carrying out its pivotal movement.

According to the invention, the second pivot bearing has a second through passage extending through the second lever part, into which a second axis section supported on the housing of the internal combustion engine can be fitted, so that the second lever part is pivotable about the second axis section for carrying out its pivotal movement.

According to the invention, the first and the second through-passages are arranged in alignment with each other, so that in this one integrally supported on the housing of the internal combustion engine, the first and second Axis portions forming axis portion is einpassbar, so that the first and second lever parts to perform their respective pivoting movements are pivotable about the axle part.

With this embodiment of the invention, a simple connection and storage of the two lever parts is realized, which advantageously allows to store and pre-assemble several switchable oscillating levers together with a plurality of non-switchable oscillating levers on a common axle part.

According to the invention, the first lever part has two arm sections extending laterally parallel to each other in a plane parallel to one another and a web section connecting the two arm sections, and wherein the second lever part is arranged between the two arm sections of the first lever part.

According to one embodiment of the invention, the first through-passage extends through both arm portions of the first lever part, so that it forms two partial passages, between which the second through-passage is arranged.

According to the invention, the first cam of the valvetrain has two cam elements of the same cam contour arranged at an axial distance from one another, wherein a respective roller is provided on the two arm sections of the first lever part, which roller is rotatably mounted on the respective arm section and which has a lateral surface for starting up a camshaft the two cam elements of the first cam, wherein respective axes of rotation of the two rollers of the first lever member are aligned, and wherein the roller of the second lever member between the two rollers of the first lever member is arranged with their respective axes of rotation parallel axis of rotation and the second cam in the axial distance between the two cam elements of the first cam is arranged.

With the invention, on the one hand, the friction losses caused by the oscillating lever in the valve drive are reduced and, on the other hand, a tilting moment across the first and second rotation axis is prevented or canceled by the flanking of the second lever part by the first lever part, whereby the frictional losses are further reduced and the service life the pivot bearing is increased.

According to the invention, the coupling means comprises a slider guide passage extending parallel to the first and second axes of rotation through the two arm portions of the first lever member and the second lever member, and in which the slider assembly is slidably disposed along the slider guide passage.

According to one embodiment of the invention, the slider assembly of the clutch device comprises: a first slider biased in a first portion of the slider guide passage formed by one of the arm portions, biased by the spring force of a spring toward the other arm portion of the first lever member, and along the slider guide passage has a length equal to a length of the first portion of the slider guide passage; a second spool disposed in contact with the first spool in a second area of the spool guide passage formed by the second lever portion and having a length along the spool guide passage that is equal to a length of the second area of the spool guide passage; and a third slider disposed in contact with the second slider in a third portion of the slider guide passage formed by the other arm portion and having a length along the slider guide passage that is smaller than a length of the third portion of the slider guide passage; the controlled third third slide from a side facing away from the second slider selectively with a force in the direction of the one arm portion of the first lever member is acted upon, so that the first slider flush upon application of the actuating force against the spring force of the spring to stop at a longitudinal end of the slide guide passage to one arm portion is retracted (accordingly located exclusively in the first region of the slide guide passage) and upon removal of the actuating force of the first Slider to the stop of the third slider at a longitudinal end opposite the other longitudinal end of the slide guide passage of the spring force is partially extended from the one arm portion (thus located both in the first region and in the second region of the slide guide passage), so that the first slider partially in is arranged the second lever part.

Accordingly, upon application of the actuating force, the second slide is positioned in the slide guide passage such that it is arranged flush in the second lever part exclusively in its second region. Thus, upon application of the actuating force, the first lever part and the second lever part are decoupled from each other in terms of their respective pivoting movements and can thus move separately according to the cam contour of the first and the second cam pivoting.

When the actuating force is removed, the second slide is accordingly positioned in the slide guide passage such that it is located partially in the second lever part and partially in the other arm section of the first lever part both in its second and in its third region. Thus, the first slider, which in this case extends from one arm portion of the first lever part into the second lever part, and the second slider, which in this case extends from the second lever part into the other arm portion of the first lever part, respectively as a locking slide. Consequently, upon removal of the actuating force, the first lever part and the second lever part are coupled with respect to their respective pivoting movements and thus pivotally move in accordance with the larger deflection causing cam contour of the respective cam contours of the first and second cam.

Due to the embodiment of the invention with at least two parallel to the oscillating lever pivot axis (first and second axis of rotation) arranged in series locking slides (first and second slide) results in more favorable ratios of displacement volume to pressure surface and switching force to slide mass, which in particular the switching time can be significantly shortened ,

Fig.1

zeigt in perspektivischer weggebrochener Ansicht gemäß der Erfindung ein Kurbelgehäuse einer Brennkraftmaschine mit einer Mehrzahl von Schwinghebeln.

Fig.2

zeigt eine perspektivische Ansicht einer an einem gemeinsamen Achsenteil gelagerten erfindungsgemäßen Anordnung von schaltbaren Schwinghebeln und nicht schaltbaren Schwinghebeln.

Fig.3

zeigt eine perspektivische Ansicht eines erfindungsgemäßen schaltbaren Schwinghebels.

Fig.4

zeigt eine Fig.3 ähnliche Ansicht des erfindungsgemäßen schaltbaren Schwinghebels mit teilweise weggeblendeten Konturen.

Fig.5

zeigt eine seitliche Draufsicht des erfindungsgemäßen schaltbaren Schwinghebels von Fig.3.

Fig.6

zeigt ausgehend von Fig.5 eine Ansicht von links des erfindungsgemäßen schaltbaren Schwinghebels von Fig.3.

Fig.7

zeigt ausgehend von Fig.5 eine Ansicht von rechts des erfindungsgemäßen schaltbaren Schwinghebels von Fig.3.

Fig.8

zeigt ausgehend von Fig.5 eine Ansicht von unten des erfindungsgemäßen schaltbaren Schwinghebels von Fig.3.

Fig.9

zeigt ausgehend von Fig.5 eine Ansicht von oben des erfindungsgemäßen schaltbaren Schwinghebels von Fig.3.

Fig.10

zeigt eine perspektivische Ansicht eines ersten Hebelteils des erfindungsgemäßen schaltbaren Schwinghebels von Fig.3.

Fig.11

zeigt eine perspektivische Ansicht eines zweiten Hebelteils des erfindungsgemäßen schaltbaren Schwinghebels von Fig.3.

Fig.12

zeigt eine Schnittansicht des erfindungsgemäßen schaltbaren Schwinghebels von Fig.3, gesehen entlang einer Schnittlinie A-A in Fig.5, wobei sich eine Schieberanordnung des Schwinghebels in einer Verriegelungsposition befindet.

Fig.13

zeigt eine Schnittansicht des erfindungsgemäßen schaltbaren Schwinghebels von Fig.3, gesehen entlang der Schnittlinie A-A in Fig.5, wobei sich die Schieberanordnung des Schwinghebels in einer Entriegelungsposition befindet.

In the following the invention will be described in more detail by means of a preferred embodiment and with reference to the attached figures.

Fig.1

shows in a perspective broken-away view according to the invention, a crankcase of an internal combustion engine having a plurality of rocking levers.

Fig.2

shows a perspective view of a mounted on a common axis part inventive arrangement of switchable rocker arms and non-switchable rocker arms.

Figure 3

shows a perspective view of a switchable rocker arm according to the invention.

Figure 4

shows one Figure 3 similar view of the switchable rocker arm according to the invention with partially hidden outlines.

Figure 5

shows a side elevational view of the switchable rocker arm of the invention Figure 3 ,

Figure 6

shows starting from Figure 5 a view from the left of the switchable rocker arm of the invention Figure 3 ,

Figure 7

shows starting from Figure 5 a view from the right of the switchable rocker arm of the invention Figure 3 ,

Figure 8

shows starting from Figure 5 a bottom view of the switchable rocker arm of the invention Figure 3 ,

Figure 9

shows starting from Figure 5 a top view of the switchable rocker arm of the invention Figure 3 ,

Figure 10

shows a perspective view of a first lever part of the switchable rocker arm of the invention Figure 3 ,

Figure 11

shows a perspective view of a second lever part of the switchable rocker arm of the invention Figure 3 ,

Figure 12

shows a sectional view of the switchable rocker arm of the invention Figure 3 , seen along a section line AA in Figure 5 , wherein a slider assembly of the rocker arm is in a locking position.

Figure 13

shows a sectional view of the switchable rocker arm of the invention Figure 3 , seen along the section line AA in Figure 5 , wherein the slider assembly of the rocker arm is in an unlocked position.

Like from the FIGS. 1 and 2 can be seen, an internal combustion engine according to the invention (not fully shown) 1, a crankcase 2, in each of which a plurality of switchable oscillating levers 10 and non-switchable oscillating levers 10 'are accommodated on a common axis part 90 supported on the crankcase 2.

In the present embodiment, the switchable rocking levers 10 are for operating unillustrated intake valves of the internal combustion engine 1 and serve the non-switchable rocker arm 10 'for actuating not shown exhaust valves of the internal combustion engine 1. The intake valves and the exhaust valves form gas exchange valves of the internal combustion engine first

For actuating the gas exchange valves, the switchable oscillating levers 10 and the non-switchable oscillating levers 10 'each have an actuating portion 11 or 11'.

The switchable oscillating levers 10 will now be described with reference to FIGS FIGS. 1 to 13 be explained in more detail.

Like from the FIGS. 1 to 13 can be seen, each switchable rocking lever 10, a first lever member 20, a second lever member 30 and a coupling device 40 for coupling together and disengaging the first lever member 20 and the second lever member 30 on.

As in particular from Figure 10 can be seen, the first lever member 20 at its one longitudinal end to a first pivot bearing 21, via which the first lever member 20 is pivotally supported about a first axis of rotation R1 on the crankcase 2 of the internal combustion engine 1. The first lever member 20 also has at its other longitudinal end at least one roller 25a, 25b, which is rotatably mounted on the first lever member 20 and which has a lateral surface 26a, 26b (see, eg Figure 7 ), on the other hand, has a start-up of a first cam (not specified in the figures) of the valve drive for generating a pivoting movement of the first lever part 20 about the first axis of rotation R1.

As in particular from Figure 11 can be seen, the adjacent to the first lever member 20 arranged second lever member 30 at its one longitudinal end to a second pivot bearing 31, via which the second lever member 30 is pivotally supported about a parallel to the first axis of rotation R1 extending second axis of rotation R2 on the crankcase 2 of the internal combustion engine 1. The second lever part 30 also has at its other longitudinal end on a roller 35 which is rotatably mounted on the second lever member 30 and which has a lateral surface 36th (see eg Figure 7 ), by contrast, has a second cam (not specified in the figures) of the valve drive for generating a pivoting movement of the second lever part 30 about the second axis of rotation R2.

As in particular from the FIGS. 2 to 5 can be seen, the first axis of rotation R1 and the second axis of rotation R2 to each other or are coincident with each other.

As in particular from Figure 10 and Fig.2 As can be seen, the first pivot bearing 21 of the first lever part 20 has a first through passage extending through the first first passage portion 22 into which a respective first intercept (not specified in the figures) of the axle portion 90 is fitted, so that the first lever member 20th to perform its pivotal movement about the respective first axis portion of the axle member 90 is pivotable.

As in particular from Figure 11 and Fig.2 As can be seen, the second pivot bearing 31 of the second lever part 30 has a second passage passage 32 extending through the second lever part 30 into which a respective second axis portion (not specified in the figures) of the axle part 90 is fitted, so that the second lever part 20 to perform its pivotal movement about the second axis portion of the axle member 90 is pivotable.

Such as out Figure 5 and Fig.2 can be seen, the first passage passage 22 of the first pivot bearing 21 of the first lever member 20 and the second passage passage 32 of the second pivot bearing 31 of the second lever member 30 are aligned to each other, so that supported on the crankcase 2 of the internal combustion engine 1 forming the first and second axis portions axis portion 90 therein fitted through the first and second through passages 22, 32 can extend therethrough.

How best from the synopsis of Figures 3 and 10 2, the first lever part 20 in detail has two arm sections 27, 28 extending parallel to one another at a lateral distance from each other in a plane, and a web section 29 interconnecting the two arm sections 27, 28, wherein the second lever part 30 is connected between the two arm sections 27, 27. 28 of the first lever part 20 is arranged.

The first through passage 22 of the first pivot bearing 21 of the first lever part 20 extends through both arm sections 27, 28 of the first lever part 20 so that it forms two partial passages 23, 24, between which the second passage passage 32 of the second pivot bearing 31 of the second lever part 30 is arranged.

Although from the FIGS. 1 to 13 can not be seen, the first cam of the valve train two with axial distance (in the direction of the first and second axes of rotation R1, R2) mutually arranged cam elements of the same cam contour, wherein the second cam of the valve gear in the axial distance between the two cam elements of the first cam of the Valve gear is arranged.

How best from the synopsis of FIGS. 7 and 10 can be seen, at the two arm portions 27 and 28 of the first lever member 20 each have a roller 25a and 25b is provided, which is rotatably mounted on the respective arm portion 27, 28 and has a lateral surface 26a and 26b, however, against starting one of the two cam elements of first cam. Respective axes of rotation R3 and R4 of the two rollers 25a and 25b of the first lever member 20 are arranged in alignment with each other. The roller 35 of the second lever part 30 is arranged between the two rollers 25a, 25b of the first lever part 20 with their respective axes of rotation R3, R4 parallel and in particular aligned or coincident axis of rotation R5.

Now with special reference to the Figures 12 and 13 the coupling device 40 described in more detail. The coupling device 40 has a slide arrangement 50 which can be moved in a controlled manner for switching over the valve stroke, so that the first and second lever parts 20, 30 can be selectively coupled to one another via the slide arrangement 50 with regard to their respective pivoting movements and can be decoupled from one another.

Figure 12 shows the slider assembly 50 of the coupling device 40 of the rocker arm 10 in a locking position, and Figure 13 shows the slider assembly 50 in an unlocked position.

More specifically, the clutch device 40 has a spool guide passage 41 which extends parallel to the first and second rotational axes R1, R2 through the two arm portions 27, 28 of the first lever member 20 and the second lever member 30 and in which the spool assembly 50 along the spool guide passage 41 slidably arranged.

The slider assembly 50 of the coupling device 40 has a first slider 51, a second slider 52 and a third slider 53, which are each formed with a circular cross-section bolt-like.

The first slider 51 is biased in a first portion of the slider guide passage 41 formed by an arm portion 27 of the arm portions 27, 28 by the spring force of a spring 42 toward the other arm portion 28 of the arm portions 27, 28 of the first lever member 20 and has along the The spool guide passage 41 has a length equal to a length of the first portion of the spool guide passage 41.

The second spool 52 is disposed in contact with the first spool 51 in a second area of the spool guide passage 41 formed by the second lever part 30 and has a length along the spool guide passage 41 equal to a length of the second area of the spool guide passage 41.

The third spool 53 is disposed in contact with the second spool 52 in a third portion of the spool guide passage 41 formed by the other arm portion 28, and has a length along the spool guide passage 41 that is smaller than a length of the third portion of the spool guide passage 41.

The third slide 53 is designed as a hydraulic piston and has an oil chamber 54 which is selectively acted upon by an oil feed 56 with oil pressure.

Thus, the third slider 53 is selectively controlled from a side facing away from the second slider 52 with a force in the direction of the one arm portion 27 of the first lever member 20 toward acted upon, so that the first slider 51 upon application of the actuating force against the spring force of the spring 42nd until stop at a longitudinal end 41a of the slide guide passage 41 is flush with it in the one arm portion 27 is retracted (as in Fig. 13 shown) and upon removal of the actuating force of the first slide 51 to the stop of the third slide 53 at a longitudinal end 41a opposite another longitudinal end 41b of the slide guide passage 41 is partially extended by the spring force of the one arm portion 27 (as in Figure 12 ), so that the first slider 51 is partially disposed in the second lever part 30.

Accordingly, upon application of the actuating force, the second spool 52 is thus positioned in the spool guide passage 41 (as in FIG Figure 13 shown) that he himself exclusively in the second area located to flush with the second lever member 30 is arranged. Thus, upon application of the actuating force, the first lever part 20 and the second lever part 30 are decoupled from each other with regard to their respective pivoting movements and can thus move separately according to the cam contour of the first and the second cam.

When the restoring force is removed, the second spool 52 is thus positioned in the spool guide passage 41 (as in FIG Figure 12 shown) that it is located both in the second and in the third area partially located in the second lever portion 30 and partially in the other arm portion 28 of the first lever portion 20. Thus, the first slider 51, which in this case extends from the one arm portion 27 of the first lever part 20 into the second lever part 30, and the second slider 52 which in this case acts from the second lever part 30 into the other arm portion 28 of the first lever part 20 extends, each as a locking slide. Consequently, when the actuating force is removed, the first lever part 20 and the second lever part 30 are coupled with respect to their respective pivotal movements and thus pivotally move in accordance with the cam contour of the respective cam contours of the first and second cam causing the greater deflection.

LIST OF REFERENCE NUMBERS

1

Internal combustion engine

2

crankcase

10

switchable rocker arm

10 '

non-switchable rocker arm

11

actuating section

11 '

actuating section

20

first lever part

21

first pivot bearing

22

first through passage

23

part passage

24

part passage

25a

caster

25b

caster

26a

lateral surface

26b

lateral surface

27

arm

28

arm

29

web section

30

second lever part

31

second pivot bearing

32

second passage

35

caster

36

lateral surface

40

coupling device

41

Slide guide passage

41a

longitudinal end

41b

longitudinal end

42

feather

50

slide arrangement

51

first slide

52

second slider

53

third slide

54

oil chamber

56

oil supply

90

axle part

R1

first axis of rotation

R2

second axis of rotation

R3

axis of rotation

R4

axis of rotation

R5

axis of rotation

Claims (3)

1. A switchable rocker lever (10) for a valve drive of an internal combustion engine (1), comprising:

   a first lever part (20) with a first pivot bearing (21), via which the first lever part (20) is pivotably supportable about a first axis of rotation (R1) on a housing (2) of the internal combustion engine (1), and at least one idler roller (25a, 25b), which is rotatably mounted on the first lever part (20) and which has a lateral surface (26a, 26b) for a first cam of the valve drive running against for generating a pivot movement of the first lever part (20) about the first axis of rotation (R1),

   a second lever part (30), which is arranged adjacent to the first lever part (20) and which has a second pivot bearing (31), via which the second lever part (30) is pivotably supportable about a second axis of rotation (R2) running parallel to the first axis of rotation (R1) on the housing (2) of the internal combustion engine (1), and an idler roller (35), which is rotatably mounted on the second lever part (30) and which has a lateral surface (36) for a second cam of the valve to run against for generating a pivot movement of the second part (30) about the axis of rotation (R2), and

   a coupling device (40) with a slide arrangement (50), which is controllably moveable for switching, so that the first and second lever parts (20, 30) via the slide arrangement (50) are selectively couplable to one another and decouplable from one another with respect to their respective pivot movements,

   wherein on one of the first and the second lever part (30, 30) an actuation section (11) for actuating a gas exchange valve of the internal combustion engine (1) is provided,

   wherein the first axis of rotation (R1) and the second axis of rotation (R2) are aligned with one another, i.e. are coincident,

   wherein the first pivot bearing (21) comprises a first through-passage (22) extending through the first lever part (20), into which a first shaft section supported on the housing (2) of the internal combustion engine (1) is fittable, so that the first lever part (20) for performing its pivot movement is pivotable about the first shaft section,

   wherein the second pivot bearing (31) comprises a second through-passage (32) extending through the second lever part (30), into which a second shaft section supported on the housing (2) of the internal combustion engine (1) is fittable, so that the second lever part (30) for performing its pivot movement is pivotable about the second shaft section,

   wherein the first and the second through-passage (22, 32) are arranged aligned with one another, so that into these an shaft part (90) forming the first and second shaft section supported on the housing (2) of the internal combustion engine (1) is fittable, so that the first and second lever parts (20, 30) are pivotable about the shaft part (90) for performing its respective pivot movements,

   wherein the first lever part (20) comprises two arm sections (27, 28) running along parallel in a plane relative to one another laterally spaced from one another and a web section (29) connecting the two arm sections (27, 28) with one another, and wherein the second lever part (30) is arranged between the two arm sections (27, 28) of the first lever part (20),

   wherein the first cam of the valve drive comprises two cam elements of the same cam contour arranged axially spaced from one another, wherein on the two arm sections (27, 28) of the first lever part (20) an idler roller (25a, 25b) each is provided, which is rotatably mounted on the respective arm section (27, 28) and which has a lateral surface (26a, 26b) for one of the two cam elements of the first cam to run against, wherein respective axes of rotation (R3, R4) of the two idler rollers (25a, 25b) of the first lever part (20) are aligned with one another, and wherein the idler roller (35) of the second lever part (30) is arranged between the two idler rollers (25a, 25b) of the first lever part (20) with an axis of rotation (R5) that is parallel to their axes of rotation (R3, R4) and the second cam of the valve drive is arranged in the axial spacing between the two cam elements of the first cams of the valve drive, and

   wherein the coupling device (40) comprises a slide guiding passage (41) which extends parallel to the first and second axes of rotation (R1, R2) through the two arm sections (27, 28) of the first lever part (20) and through the second lever part (30) and in which the slide arrangement (50) is displaceably arranged alongside the slide guiding passage (41).
2. The switchable rocker lever (10) according to Claim 1, wherein the first through-passage (22) extends through both arm sections (27, 28) of the first lever part (20), so that it forms two part passages (23, 24), between which the second through-passage (32) is arranged.
3. The switchable rocker lever (10) according to Claim 1, wherein the slide arrangement (50) of the coupling device (40) comprises:

   a first slide (51), which, arranged in a first region of the slide guiding passage (41) formed by one of the arm sections (27) is preloaded by the spring force of a spring (42) in the direction of the other arm section (28) of the first lever part (20) and which along the slide guiding passage (41) has a length which is equal to a length of the first region of the slide guiding passage (41),

   a second slide (52), which is arranged in touch contact with the first slide (51) in a second region of the slide guiding passage (41) formed by the second lever part (30) and which along the slide guiding passage (41) has a length which is equal to a length of the second region of the slide guiding passage (41), and

   a third slide (53) which in touch contact with the second slide (52) is arranged in a third region of the slide guiding passage (41) formed by the other arm section (28) and which along the slide guiding passage (41) has a length that is smaller than a length of the third region of the slide guiding passage (41),

   wherein the third slide (53) is loadable from a side facing away from the second slide (52) in a controlled selective manner with an actuating force in the direction of the one arm section (27) of the first lever part (20), so that the first slide (51) upon loading of the actuating force is retracted against the spring force of the spring (42) up to a stop at a longitudinal end (41a) of the slide guiding passage (41) into an arm section (27) flush thereto and upon removal of the actuating force the first slide (51) is partially extended out of the one arm section (27) by the spring force up to the third slide (53) striking against the stop on another longitudinal end (41b) of the slide guiding passage (41) located opposite the one longitudinal end (41a), so that the first slide (51) is partly arranged in the second lever part (30).

Images