LOCKING DEVICE FOR A SWITCHABLE VALVE DRIVE COMPONENT

Abstract

The invention relates to a locking device for a switchable valve drive component, including a first locking body and a second locking body which can be brought into engagement with one another or out of engagement in order to couple to one another or to uncouple two component parts arranged movably with respect to one another, wherein at least one of the two locking bodies has at least one curved surface. In order to increase the wear resistance of the locking device, provision is made for at least one of the two locking bodies to have a plurality of curved surfaces of which the respective curvature is described by radii of identical length having constructional center points spaced apart from one another.

Claims

1. A locking device for a switchable valve train component comprising a first locking body and a second locking body that are brought into engagement with each other or are brought out of engagement with each other in order to couple or decouple two components arranged so that they are movable relative to each other, at least one of the first or second locking bodies has multiple curved surfaces each with curvatures that are described by radii of identical length with structural center points that are spaced apart from each other.

2. The locking device according to claim 1, wherein the first locking body is constructed as a cylindrical piston with a circular outer circumferential surface, the second locking body has a holder with a roundly tapered cross-section for the first locking body, the roundly tapered holder is formed by two of the curved surfaces, the respective curvatures of the two surfaces of the roundly tapered holder are defined by the radii having the identical lengths, which have the structural center points that are different, so that, in a locked state, two contact lines are active in a longitudinal direction of the first and second locking bodies between the first locking body and the second locking body.

3. The locking device according to claim 1, wherein the first locking body is constructed as a half-cylindrical piston that has a roundly tapered cross-section with two of the curved surfaces and for which a tip of the round taper of the piston is flattened, the curvatures of the two surfaces of the round taper of the piston are formed by the two radii having the identical lengths, which start from the structural center points that are different, and the second locking body is constructed as a hollow cylindrical holder for the first locking body, so that, in the locked state, two contact lines are active in a longitudinal direction of the first and second locking bodies between the first locking body and the second locking body.

4. The locking device according to claim 1, wherein the locking device is integrated in a switchable valve train component constructed as a switchable cam follower of a valve train of an internal combustion engine, the locking device is active between two rocker arms of the switchable cam follower supported so that the two rocker arms are pivotable relative to each other, and for which the locking device is installed in a longitudinal direction or in a transverse direction of the switchable cam follower.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The invention is explained in more detail below with reference to the accompanying drawing using two embodiments. Shown therein are

[0021] FIG. 1 a first locking device constructed according to the invention for a switchable valve train component in cross-section,

[0022] FIG. 2 a second locking device constructed according to the invention for a switchable valve train component in cross-section, and

[0023] FIG. 3 a locking device for a switchable valve train component in cross-section according to the prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The locking devices A, B shown in FIGS. 1 and 2 can be integrated, for example, in a not-shown switchable cam follower of a valve train. The switchable cam follower has, for example, two not-shown rocker arms that are connected to each other so that they can pivot relative to each other. The locking devices A, B are used, for example, for the switchable coupling of a switching motion of the cam follower in order to switch between different cam strokes that are to be transferred when the internal combustion engine is running to an inlet valve or to an exhaust valve of an internal combustion engine. In this context, refer to the publications cited farther above.

[0025] The locking device A according to FIG. 1 has a first locking body 1 and second locking body 2. The first locking body 1 is constructed as a cylindrical piston 1′ that has a circular cross-section with a first radius R1. The piston 1′ engages with an axial longitudinal half, viewed in the longitudinal direction 3, in an approximately cylindrical, axial holder 4 of the second locking body 2. This holder 4 has a roundly tapered cross-sectional profile with two curved surfaces 5, 6 whose curvatures are defined by a second radius R2 and by a third radius R3, respectively. The second radius R2 and the third radius R3 are each of identical length, but their respective not exactly described structural center points are spaced apart from each other so that, as a result, the roundly tapered cross-sectional profile is produced that is similar to a gothic arc.

[0026] The piston 1′ nestles within the holder 4 with its outer circumferential surface 7 against the two curved surfaces 5, 6, so that exactly two contact lines 8, 9 are formed. A one-sided linear contact susceptible to wear on only one contact line is avoided. The lateral alignment of the piston 1′ is defined by the roundly tapered cross-sectional profile of the holder 4 with two line contacts.

[0027] The locking device B according to FIG. 2 has a first locking body 10 and second locking body 12. The first locking body 10 is constructed as a half-cylindrical piston 10′ with a cut radial tip 14. In this way, the piston 10′ has two curved surfaces 15, 16 that extend axially and have curvatures defined by a fifth and sixth radius of curvature R5, R6, respectively. The fifth radius R5 and the sixth radius R6 are of identical length, but their respective not exactly described structural center points are spaced apart from each other, so that, as a result, the cross-sectional geometry that can be seen in FIG. 2 for the first locking body 10 shown there is produced. The piston 10′ engages with its axial longitudinal half shaped as described in the hollow cylindrical holder 12′ of a second cylindrical locking body 12. The holder 12′ consequently has an inner circumferential surface 13 with a circular cross-section with a fourth radius of curvature R4 against which the piston 10′ nestles, viewed in the longitudinal direction 3, with exactly two contact lines 18, 19. A one-sided line contact susceptible to wear on only one contact line is therefore successfully prevented.

[0028] For comparison with the locking devices A, B according to the invention, FIG. 3 shows a conventional locking device C. This locking device C has a first locking body 1 and second locking body 22. The first locking body 1 is constructed as a cylindrical piston 1′ with a circular outer circumferential surface 7, wherein the first radius R1 here also defines the curvature of the cylindrical piston 1′. The second locking body 22 has a cylindrical holder 24 or hole whose inner circumferential surface 25 is described with respect to its curvature by a seventh radius R7. The seventh radius R7 is here greater than the first radius R1. The first locking body 1 nestles, viewed in the longitudinal direction 3, with its radial outer surface 7 against the inner circumferential surface 25 of the cylindrical holder 24 under formation of exactly one contact line 26, wherein the lateral position of the contact line 26 varies as a function of the locking play. It is easily comprehensible that in this known locking device C, a strong wear takes place in the area of the only contact line 26.

LIST OF REFERENCE NUMBERS

[0029] 1 First locking body [0030] 1′ Piston [0031] 2 Second locking body [0032] 3 Longitudinal axis of the piston 1′ [0033] 4 Roundly tapered holder in second locking body 2 [0034] 5 First surface of the holder 4 [0035] 6 Second surface of the holder 4 [0036] 7 Outer circumferential surface of the first locking body 1 [0037] 8 First contact line [0038] 9 Second contact line [0039] 10 First locking body [0040] 10′ Half-cylindrical piston [0041] 12 Second locking body [0042] 12′ Hollow cylindrical holder of the second locking body 12 [0043] 13 Cylindrical inner circumferential surface of the second locking body 12 [0044] 14 Cut tip of the second locking body 12 [0045] 15 First roundly tapered surface of the first locking body 10, 10′ [0046] 16 Second roundly tapered surface of the first locking body 10, 10′ [0047] 18 First contact line [0048] 19 Second contact line [0049] 22 Second locking body [0050] 24 Cylindrical holder of the second locking body 22 [0051] 25 Inner circumferential surface of the second locking body 22 [0052] 26 Contact line [0053] A Locking device [0054] B Locking device [0055] C Locking device [0056] R1 First radius [0057] R2 Second radius [0058] R3 Third radius [0059] R4 Fourth radius [0060] R5 Fifth radius [0061] R6 Sixth radius [0062] R7 Seventh radius