EP2473716B1 - Device for adjusting a camshaft of an internal combustion engine - Google Patents

Description

The present invention relates to a device for adjusting the camshaft of an internal combustion engine according to the preamble of the main claim.

Such a device is known from PCT / EP 2008/006417 The applicant discloses and describes how an actuating element (typically a plunger or the like actuating pin) can effect an axial, predetermined adjustment of the camshaft by interaction with a profile associated with the camshaft. This is particularly relevant for those applications in which different cam tracks are to be assigned switchable to an internal combustion engine.

From the prior art, it is from the DE 196 11 641 C1 known to provide for each axial displacement position of the Hubprofilanordnung a suitably driven pin, which can then cause a respective intended axial displacement. However, this is structurally complex and requires a lot of installation space at the site.

From the used as a generic PCT / EP 2008/006417 It is also known, the Hubprofil with a plurality of cam grooves for cooperation with the electromagnetically driven ram unit in such a way that the control grooves penetrate into different groove depths and thus by different (suitably set) penetration depths of the plunger unit can actuate the camshaft in the desired manner. Also from the DE 10 2007 037 232 A1 Such a device is known.

However, the known from the generic state of the art ram unit together with the cooperating electromagnetic actuator is structurally complex, for the realization of the known groove engagement functionality in two penetration depths, the known ram unit has an arrangement consisting of an inner plunger (small diameter) and a surrounding outer plunger larger Diameter, which are assigned to the respective control grooves and the corresponding penetration depth.

It is therefore necessary to realize the movement behavior of the inner and outer tappets of the known device in a suitable constructive and control-related manner, which is complex and potentially error-prone.

Object of the present invention is therefore to improve a device for camshaft adjustment according to the preamble of the main claim in terms of a simplified structural realization, thus potentially increased reliability and reduction of the required components and assembly costs.

The object is achieved by the device having the features of the main claim; advantageous developments of the invention are described in the subclaims.

In accordance with the invention advantageously, the profile element with two control grooves of different penetration depths is actuated by a plunger unit, which has a constant outside diameter at the engagement end in both penetration depths. This is inventively made possible in that the (preferred and typically designed as a one-piece, pin-like cylindrical body) ram unit is actuated by a bi- or tristable actuator which moves along the direction of movement an anchor unit and both for the first penetration depth (with associated first stable Positioning) and for the second penetration depth (with an associated second stable setting position) offers respective reliably controllable anchor positions. In addition, the invention provides that the anchor unit according to the invention can be moved to a third setting position, which is out of engagement with the first and the second control groove.

Thus, according to the invention, the realization of the two different penetration depths with the tappet unit is advantageously made possible at first (Single) axial mounting location can be provided and depending on the set activation for the parking positions according to the control grooves (grooves) can selectively select and run, which then the rotation of the Hubprofilelements the intended axial displacement (in the respectively desired or set direction) is effected.

It is provided on the one hand according to the invention and preferred to provide the first and the second control grooves adjacent to each other in a common and / or integrally formed Hubprofilelement, these further education at least partially merge into one another. In this way, then, in the manner of a switch or branch along a groove track, by suitable Eindringtiefenverstellung in a particularly reliable manner, the camshaft adjustment.

In this case, the geometry of the control grooves is particularly preferably configured such that an axial movement in a first direction of the camshaft can be effected by means of a first control groove of a first depth and a subsequent setting of the ram unit to a second penetration depth then moves off the second control groove and the camshaft counteracts first axial direction leads back.

In addition, according to further development, the system can be supplemented by a third control groove, which then allows an axial movement (as well as a respective axial movement back) in a second, the first direction opposite axial direction of the camshaft.

In a structurally particularly preferred manner, the armature unit is implemented as part of the electromagnetic actuator by means of at least one permanent magnet unit, it is useful to achieve a bi- or tristable device to design the armature unit with a pair of axially opposite, further education disk-shaped magnet.

In a further advantageous development, the permanent magnets can then be used to enable a currentless-stable state (the term "currentless-stable" in the context of the invention should be understood to mean that a parking position by the anchor unit (and the associated ram unit ) is reached and held without current supply to the coil unit is required).

In a structurally particularly elegant manner, it is also possible to make the electromagnetic adjusting device tristable in such a way that a third (preferably stable) position is achieved in the axial direction between two axial end positions determined by adhering respective permanent magnet units to a stationary core region on the one hand, that a stable intermediate state is achieved by mutual, oppositely directed attraction effect of permanent magnets, additionally and / or alternatively by AC excitation of the coil means a (stable) middle position of the armature unit can be achieved, in which none of the permanent magnet units adheres to a stationary core Rather, permanent reverse polarity by the AC signal triggers this state (causing the tristurbance).

Within the scope of further preferred embodiments of the invention, it is possible for the plunger unit to interact with the armature unit in such a way that the (more preferably one-piece, metallic) plunger unit is detachably adhered to the armature unit by the action of the magnet (preferably on the front side) on the armature unit; insofar as maximum flexibility in use and installation is given.

It is then additionally advantageous to realize the ram unit in such a way that, at one end, in the direction of the permanent magnet unit, it has favorable magnetic properties for adhesive cooperation with the armature unit, at the other end, and for engaging in the profile element or a respective control groove suitable tough or wear-resistant material optimized.

As a result, a device for adjusting the camshaft of an internal combustion engine is realized by the present invention in a surprisingly simple and effective manner, which combines constructive simplicity with compact design and high reliability.

Fig. 1

eine seitliche Ansicht eines Hubprofilelements gemäß einer ersten Ausführungsform der Erfindung mit partiell dargestellten Steuernuten;

Fig. 2:

eine radiale Abwicklung eines vollständigen Steuernutverlaufs der Vorrichtung gemäß Fig. 1;

Fig. 3, Fig. 4:

Ansichten zum Verdeutlichen, wie eine Stößeleinheit im Eingreifen in das Hubprofilelement der Fig. 1 eine axiale Bewegung in rechter Richtung erzeugt (wobei die Stößeleinheit in eine erste, verminderte Eindringtiefe angesteuert wird);

Fig. 5:

eine Darstellung des Hubprofilelements der Fig. 1 in relativ zur Fig. 1 verdrehter Ansicht;

Fig. 6:

eine Darstellung analog Fig. 2 zum Verdeutlichen eines Stellvorgangs (bzw. Verschiebeweges) entlang einer zweiten Steuernut zum Rückstellen der Nockenwelle aus der durch die Fig. 2 bis 4 verdeutlichten axialen Verschiebeposition;

Fig. 7,Fig. 8:

Darstellungen analog der Fig. 3, 4 zum Verdeutlichen eines Stößeleingriffs in eine zweite Eindringtiefe (Fig. 7) zum Bewirken der Rückstellposition, wobei, gemäß Fig. 8, durch Wirkung des Nutenbahnverlaufs die Stößeleinheit graduell aus der zweiten Verschiebeposition herausgedrückt wird;

Fig. 9, Fig. 10:

eine Darstellung der Abwicklung des Nutenverlaufs gemäß Fig. 2, Fig. 6 zum Verdeutlichen eines Stell- (Fig. 9) sowie Rückstell- (Fig. 10) Vorgangs in entgegengesetzter Richtung des Beispiels der Fig. 2, Fig. 6;

Fig. 11:

eine Perspektivansicht zum Verdeutlichen des konstruktiven Aufbaus der elektromagnetischen Stellvorrichtung um Realisieren eines tristabilen axialen Stellens zwischen den drei Stellpositionen;

Fig. 12:

eine Detailansicht des Eingriffsendes der elektromagnetischen Stellvorrichtung zum Verdeutlichen, wie eine stiftförmige Stößeleinheit durch Wirkung von stirnseitig an der Ankereinheit vorgesehenen Permanentmagneten an der Ankereinheit der elektromagnetischen Stellvorrichtung lösbar haftet;

Fig. 13:

eine schematische Schnittansicht zum Verdeutlichen magnetischer Flüsse und Kräfte bei der Realisierung einer mittleren Ankerposition für einen tristabilen Aktuator und

Fig. 14:

eine Schnittansicht durch eine Steuernut zum Verdeutlichen der Proportionen und der Relativgeometrie für eine erste (flache) und zweite (tiefe) Nutentiefe.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawings; these show in:

Fig. 1

a side view of a Hubprofilelements according to a first embodiment of the invention with partially shown control grooves;

Fig. 2:

a radial development of a complete Steuerutverlaufs the device according to Fig. 1 ;

3, 4:

To illustrate how a ram unit in engaging in the Hubprofilelement the Fig. 1 generates an axial movement in the right direction (wherein the plunger unit is driven in a first, reduced penetration depth);

Fig. 5:

a representation of the Hubprofilelements the Fig. 1 in relative to Fig. 1 twisted view;

Fig. 6:

a representation analog Fig. 2 for clarifying a setting process (or displacement path) along a second control groove for returning the camshaft from the through the Fig. 2 to 4 clarified axial displacement position;

Fig. 7, Fig. 8th:

Representations analogous to Fig. 3, 4 to illustrate a ram engagement in a second penetration depth ( Fig. 7 ) for effecting the reset position, wherein, according to Fig. 8 , by the effect of Nutenbahnverlaufs the plunger unit is gradually pushed out of the second displacement position;

Fig. 9, Fig. 10:

a representation of the processing of Nutenverlaufs according to Fig. 2, Fig. 6 to illustrate an actuating ( Fig. 9 ) and reset ( Fig. 10 Operation in the opposite direction of the example of Fig. 2, Fig. 6 ;

Fig. 11:

a perspective view illustrating the structural design of the electromagnetic actuator to realize a tristable axial positioning between the three control positions;

Fig. 12:

a detail view of the engagement end of the electromagnetic actuator to illustrate how a pin-shaped ram unit by the action of frontally provided on the armature unit permanent magnet on the armature unit of the electromagnetic actuator releasably adhered;

Fig. 13:

a schematic sectional view to illustrate magnetic fluxes and forces in the realization of a middle anchor position for a tri-stable actuator and

Fig. 14:

a sectional view through a control groove to illustrate the proportions and the relative geometry for a first (flat) and second (deep) groove depth.

Based on the representations in the Fig. 1 to 4 describes how the camshaft adjustment device according to a first preferred embodiment of the invention, an axial movement of the camshaft in the direction of the arrows 10 (ie in the plane of the right) causes.

This shows the wide view of the Fig. 1 (This is incomplete with respect to adjacent further grooves), as with a on a (not shown) camshaft of an internal combustion engine rotatably mounted Hubprofilelement 12 a control groove 14, which (see the lower portion of the illustration of Fig. 1 ) From a common groove bottom in a left side branching Nutverlauf 16 a first, shallower depth (indicated by the dashed line in the settlement of Fig. 2 ) and a right side deeper groove course 18 (continuous black course in the settlement of Fig. 2 ) branches. Accordingly, it is in the position of Fig. 1 assuming ram position in the groove input 14, it is possible to follow either the further path of the shallower groove 16 or the deeper groove 18 by suitable selection (adjustment) of the ram depth (corresponding to a respective position of the electromagnetic actuator actuating the ram).

The embodiment of Fig. 1 to 4 illustrates how by moving a plunger unit 17 in a first (shallower) penetration depth corresponding to the groove depth of the groove 16, a rightward movement along the arrow 10 is performed. This movement is through the single arrows 20 in Fig. 2 indicated in the side views of the Fig. 3, 4 (which show correspondingly more rotational positions of the Hubprofilelements) illustrates.

Accordingly, as a result of the continued rotation of the (non-rotatably seated on the camshaft) Hubprofilelements relative to the stationary in the radial direction ram an axial thrust, which the Hubprofilelement and thus the camshaft in the in Fig. 4 in the direction of arrow 10 shown to the right.

The Fig. 5 to 8 illustrate the axial counter-movement, whereby the camshaft can be moved back to the starting position: This path is shown by a Steuerutverlauf 22 (solid black line, illustrates the deep groove bottom), which is approached by the plunger unit 17, which in a second penetration depth is brought according to the course 22. The arrowhead 24 illustrates the Movement, starting from an initial, axially displaced position, in turn, the plunger unit 17 would engage in a recessed groove bottom (this time but in the second, deeper penetration depth) according to reference numeral 26 and on the recessed path 22 (along the arrows 24) remains (via the radial position of the Fig. 7 ) until the home position corresponding to the shift state of Fig. 1, Fig. 2 (before moving there) is achieved.

Analogous to this pushing back and forth in a first axial displacement direction illustrates only exemplary, the further illustration of FIGS. 9, 10 the back and forth in the opposite axial direction: So, for example, starting from the central position, now by moving the ram unit 17 in the deep (second) penetration position of the path along the groove 18 take place (arrow 28), with the result that a (in the figure level) left movement is controlled. The return from this adjustment position back to the middle position ( FIG. 10 ) Then takes place by means of a groove 30 of the first depth (dashed line or arrowhead 32) in which case the ram unit 17 engages again with a reduced penetration depth.

In this way, by moving a pin-like cylindrical ram unit 17 with only one (preferably constant) outer diameter in the engagement area in the grooves induce the same (relatively complex) axial movement of a camshaft, as in the prior art by an axial arrangement of outer and inner tappets (or a plurality of axially adjacent plunger) has been possible.

Based on FIGS. 11 to 13 an embodiment is explained how an electromagnetic actuator for moving the plunger unit 17 can be realized in the respective parking positions. Shown in the perspective view of a housing assembly consisting of two nested U-shaped brackets 40, 42, which offer an opening 44 in their respective connection region through which a Anchor unit 46 is guided. The armature unit 46 has a permanent magnet arrangement 50 at both ends of a central elongated-cylindrical middle section 48, which supports a disc-shaped permanent magnet at both ends and offers an outer surface 52 on which the tappet unit 17 (held by permanent magnet action) is detachably seated.

By suitable control of a stationary coil unit 54, the armature unit is moved between respective axial end positions, these end positions being determined by a stop (and permanent magnetic adhesion state of a respective permanent magnet). In order to achieve a tristability which is advantageous in accordance with the invention, it is additionally provided that the armature unit is brought into an axial center position by suitable pulse-shaped control of the coil unit 54 in which none of the permanent magnet units 50 adheres to a housing bottom or a magnetically active core and thus assumes a stable center position. In addition, according to the invention, it is advantageous to induce this middle position of the tristability by means of suitable alternating current control of the permanent magnet means. The Fig. 13 illustrates corresponding courses of the magnetic flux for the tristable center position. It is clarified how (via corresponding flux guide elements and geometric design of the core) a respective magnetic flux of the permanent magnets 50 is closed by the core, so that, corresponding to the two mutually directed force arrows 58, a stable center state (only effected by the respective attraction on the core region performing permanent magnet) is created and causes a stable center position of the armature unit. By pulse-shaped energizing the coil unit 54, the armature unit can be moved into this position and switched from this to one of the two end positions; In addition, the mentioned AC control of the coil unit provides for such a center position.

The Fig. 14 clarifies, as far as the side views or unrolled views of Hubprofilelemente according to Fig. 1 to 10 in addition, a possible Groove geometry with a groove cross-section of a first cam groove of a first penetration depth 60 (dashed line), in comparison to the groove depth or groove geometry of a second cam groove of a relatively deeper groove depth. This illustration is, as well as the schematic representations of Fig. 1 to 10 purely schematic and not restrictive, but the geometries, Nutenverläufe and other, lying within the skill of the art embodiments of a particular application would suitably adapt.

Claims (14)

1. Device for adjusting the camshaft of an internal combustion engine, comprising a lift profile element (12) which is provided on or against an axially displaceably mounted camshaft for rotation therewith and which provides a control groove, and comprising a control unit for producing a predetermined axial movement of the camshaft, the control unit having a tappet unit (17) which is preferably movable radially with respect to the camshaft in a movement direction and which is designed to engage in the lift profile element in a controllable manner, and the lift profile element forming a first control groove (16) which is designed to interact with the tappet unit at a first penetration depth so as to describe a first axial movement of the camshaft, and the lift profile element forming a second control groove (18, 22) which is designed to interact with the tappet unit at a second penetration depth, which differs from the first penetration depth, so as to describe a second axial movement, which differs from the first axial movement, of the camshaft, characterised in that the tappet unit (17) has a constant outer diameter at the engagement end at the first penetration depth and at the second penetration depth, and is driven in the movement direction by an electromagnetic adjusting device which provides, in a controllable manner, a first stable adjusting position for the first penetration depth, a second stable adjusting position for the second penetration depth and a third adjusting position for a state in which the tappet unit does not engage in the first and second control groove.
2. Device according to claim 1, characterised in that the tappet unit (17) is formed as a body in one piece, having a constant outer diameter.
3. Device according to either claim 1 or claim 2, characterised in that the first and the second control groove are provided adjacent to each other in a common lift profile element (12) and/or a lift profile element (12) formed in one piece.
4. Device according to any of claims 1 to 3, characterised in that the first and the second control groove in the lift profile element merge, at least in regions.
5. Device according to any of claims 1 to 4, characterised in that the tappet unit is pin-shaped and cylindrical.
6. Device according to any of claims 1 to 5, characterised in that the first and the second control groove are formed such that owing to the action of the control unit which controls the tappet unit, the camshaft can be adjusted by means of the first axial movement and the second axial movement from an initial position into a first axially displaced position and back into the initial position.
7. Device according to claim 6, characterised in that the lift profile element has a third control groove adjacent to and/or overlapping in part with the first and the second control groove, and the third control groove describes a third axial movement of the camshaft, the third control groove being formed and/or arranged such that owing to the action of the control unit which controls the tappet unit, the camshaft can be moved from the initial position or from the first axially displaced position into a second axially displaced position, which is different from the initial position and the first axially displaced position.
8. Device according to claim 7, characterised in that the first, second and third control grooves are formed such that owing to the action of the control unit which regulates the tappet unit, the camshaft can be adjusted as desired between three axial displacement positions which are different from one another.
9. Device according to any of claims 1 to 8, characterised in that the electromagnetic adjusting device has an armature unit (46) which is movable relative to a stationary coil unit and as a reaction to a supply of current thereof along a longitudinal movement axis between at least two adjusting positions, and which has engagement means on the end for interaction with the tappet unit, the at least two adjusting positions being adjusting positions which are stable without current.
10. Device according to claim 9, characterised in that the electromagnetic adjusting device is formed to bring the armature unit into a third adjusting position, the third adjusting position being located in the direction of the longitudinal movement axis between the first and the second adjusting position.
11. Device according to either claim 9 or claim 10, characterised in that the armature unit has permanent magnet means (50) in the form of at least one, preferably two, permanent magnets, which are formed to interact with a stationary core region and to produce and/or hold at least one of the adjusting positions which are stable without current.
12. Device according to any of claims 9 to 11, characterised in that the tappet unit (17) is fastened detachably to the armature unit (46) by means of the permanent magnet effect.
13. Device according to any of claims 1 to 12, characterised in that in the movement direction, the tappet unit comprises connected materials which are not detachable and have different strength and/or magnetic characteristics.
14. Device according to any of claims 1 to 13, characterised in that the electromagnetic adjusting device has a housing which is formed as a pair of bracket-shaped housing elements (40, 42) provided nested into each other and/or against each other, through which an armature unit (46), driving the tappet unit, extends axially.

Images