EP2132417B1 - Device for camshaft adjustment in an internal combustion engine - Google Patents

Abstract

A device for camshaft adjustment in an internal combustion engine which has an inner rotor rotationally fixed to a camshaft. The inner rotor is rotationally adjustable relative to an outer rotor that is driveably connected to a crankshaft. At least one hydraulic chamber limited by side walls is introduced into the outer rotor and is divided into two partial chambers by an element extending radially outward from the inner rotor. To lock relative movement between the inner and outer rotor, two locking pins penetrating the inner rotor axially engage in two recesses of one of the side walls designed as a locking cover. To adjust the play of the locking pins in the recesses, at least one of the recesses has a stop surface for the locking pin, the position of which changes as viewed circumferentially with the radial distance from the axis of the inner rotor.

Description

Field of the invention

The invention relates to a device for adjusting the camshaft of an internal combustion engine, which has a rotatably connected to a camshaft inner rotor which is rotatably adjustable relative to an outer rotor rotatably connected to a crankshaft, wherein in the outer rotor at least one hydraulic chamber limited by side walls is introduced, said is divided by a radially outwardly extending from the inner rotor element into two sub-chambers, wherein for locking the relative movement between the inner rotor and outer rotor two inner rotor axially passing through locking pins are provided which can engage in two recesses, which are introduced into one of the side walls designed as a locking lid and wherein at least one of the two recesses in the locking cover has a stop surface for the locking pin whose position is viewed in the circumferential direction with the radial distance from the A. Chse of the inner rotor changed. Preferably, the position of both stop surfaces changes with the radial distance from the axis of the inner rotor.

Background of the invention

A camshaft adjusting device of this kind is known from US 2001/0039932 A1 known. Similar solutions show the US 2003/012485 A1 , the US 6,155,221 , the US 2006/0081204 A1 , the WO 2005/108752 A1 and the US Pat. No. 6,450,137 B2 , The device has an inner rotor, which is screwed by a central screw with the camshaft of the internal combustion engine. The outer rotor is connected to the crankshaft via a chain or via a toothed belt in active connection. Between the inner rotor and the outer rotor can - be initiated via an external hydraulic actuation - a relative rotational movement. For this purpose, the inner rotor is designed as an impeller having grooves for receiving wings. The wings divide a hydraulic chamber into two areas. By appropriate action on the respective section of the hydraulic chamber, adjustment of the inner rotor relative to the outer rotor can take place between an "early stop" and a "late stop".

The camshaft adjuster thus has the function of changing the angular position of the camshaft relative to the crankshaft of the internal combustion engine during operation. The angular position which can be set with the described embodiment is stored in a characteristic map in an engine control unit and results essentially from the two parameters engine load and engine speed. During operation of the engine, the camshaft adjuster operates on the vane-cell principle, that is, by generating an oil pressure difference in the hydraulic chambers adjusted the camshaft adjuster in the direction of "early stop" or "late stop".

When starting the engine, the problem arises that there is not enough oil pressure in the engine's oil circuit to keep the phaser in a particular position. The result is that the camshaft phaser starts to swing uncontrollably. Furthermore, noises are caused by the striking of the wings on the outer rotor (stator).

It has become known to solve the mentioned problem in that an axial locking between the inner rotor and a laterally arranged locking cover in the camshaft adjuster is made. Mostly a lock was made in one of the end stop positions "late" or "early". It can be adjusted relatively easily by appropriate positioning of the inner rotor to the outer rotor before mounting the camshaft adjuster the locking clearance. On the one hand, this game must not be too big, as otherwise unwanted noises occur, on the other hand It must not be too small, otherwise the locking pin (locking piston) can no longer reliably lock or unlock.

However, the locking in the end positions "early" and "late" also has disadvantages, so that there is a desire to make a lock in a middle position between "early" and "late" can. The "center lock" differs from the "end stop lock" in that the camshaft adjuster is locked in a defined angular position between the two end positions "early" and "late", which is particularly advantageous when starting the engine.

The above US Pat. No. 6,450,137 B2 This is made possible by two locking pins (locking pistons) that pass axially through the inner rotor. The locking pins can engage with their one axial end in two recesses which are introduced into one of the side walls of the camshaft adjuster designed as a locking cover. The two locking pins are arranged parallel to each other and radially spaced from each other.

A disadvantage of this design is that due to the tolerance chain of the components, d. H. Namely, the locking pins in their holes and the recesses in the locking lid, a locking clearance results, which - in contrast to the one at the Endanschlagsverriegelung - is not adjustable before mounting.

The locking clearance is essentially determined by the geometric distance between the two holes in the inner rotor for receiving the locking pins and the distance between the two locking recesses (locking slots) in the locking cover. The distance is therefore essentially determined by the manufacturing tolerances, wherein in prior art solutions no influence during assembly is possible. Of influence are also the game of locking pins in their mounting holes in the inner rotor, the radial bearing clearance of the inner rotor in the outer rotor, the centering of the locking cover on the outer rotor and the dimensional accuracy of the locking link. All these effects make it particularly difficult to maintain a defined locking clearance in a camshaft adjuster of the generic type.

Object of the invention

The present invention is therefore the object of a camshaft adjuster of the type mentioned in such a way that it is possible to obtain even when using a lock in the middle position between "early" and "late" a largely backlash-free arrangement, so that in particular the Noise level remains low. Furthermore, the function of locking and unlocking should be ensured by choosing an optimal, low game.

Summary of the invention

The solution of this object by the invention is characterized in that the side wall formed as a locking lid of the device and the outer rotor are formed so that the locking cover can be set in different radial relative positions to the outer rotor.

A preferred embodiment of the invention provides that at least one stop surface, preferably both stop surfaces, has a straight course. The stop surface may include an angle to the radial direction.

Furthermore, it can be provided that the abutment surfaces are arranged so that their distance increases in the circumferential direction increases with increasing radial distance from the axis of the inner rotor. It is also possible the reverse configuration, ie that the stop surfaces are arranged so that their distance in the circumferential direction decreases with increasing radial distance from the axis of the inner rotor.

For a simple mounting option with adjustment of the game between stop surfaces and locking pins, it is also very advantageous if it is provided that holes for the passage of fasteners, in particular screws, are arranged in the locking cover or in the outer rotor, the radial displacement between the locking cover and the outer rotor allow.

The locking cover is preferably disc-shaped.

The function of the locking cover is on the one hand the sealing of the oil chambers and on the other hand, the transmission of the drive torque from the crankshaft to the camshaft when the camshaft adjuster is axially locked.

With the proposed embodiment of a camshaft adjuster, it is possible to achieve a "center lock" in which when using the two locking pins a precisely adjustable game remains that maintains the functionality of the camshaft adjuster and leads to a favorable operating behavior, in particular as regards the noise. The game for the locking pins can be easily adjusted during assembly of the camshaft adjuster.

In particular, it does not have to be accepted that in the case of camshaft adjusters of the generic type there is too great a locking clearance, as is often the case in previously known solutions.

Advantageously, no change in the axial space is required, ie the lid width or thickness is unchanged in comparison with prior art solutions.

The proposed solution is also applicable when the camshaft adjuster an additional locking piston for an additional Endanschlagsverriegelung is, as provided in some constructions.

Brief description of the figures

Fig. 1

schematisch die Seitenansicht eines Nockenwellenverstellers, der mit einer Nockenwelle verbunden ist,

Fig. 2

eine zu Fig. 1 alternative Ausgestaltung des Nockenwellenvers- tellers,

Fig. 3

die Vorderansicht des Nockenwellenverstellers im Schnitt A-B gemäß Fig. 1, dargestellt ohne Nebenaggregate,

Fig. 4

den oberen Teil der Vorderansicht gemäß Fig. 3 in vergrößerter Darstellung, wobei der Innenrotor, der Außenrotor und die als Verriegelungsdeckel ausgebildete Seitenwand angedeutet sind, und

Fig. 5

eine zu Fig. 4 alternative Ausgestaltung der Erfindung.

In the drawings, embodiments of the invention are shown. Show it:

Fig. 1

schematically the side view of a camshaft adjuster, which is connected to a camshaft,

Fig. 2

one too Fig. 1 alternative embodiment of the camshaft adjuster,

Fig. 3

the front view of the camshaft adjuster in section AB according to Fig. 1 , shown without ancillaries,

Fig. 4

the upper part of the front view according to Fig. 3 in an enlarged view, wherein the inner rotor, the outer rotor and designed as a locking lid side wall are indicated, and

Fig. 5

one too Fig. 4 alternative embodiment of the invention.

Detailed description of the figures

In Fig. 1 and Fig. 2 is only very schematically illustrated a phaser 1, with which a camshaft 2 can be adjusted relative to the crankshaft with respect to the angle of rotation. An inner rotor 3 and an outer rotor 4 of the camshaft adjuster 1 are indicated, the inner rotor 3 being rotated relative to the outer rotor 4, as will be seen in greater detail below can to move the camshaft between an "early" working position and a "late" working position. The camshaft adjuster 1 has a first side wall 5 and a second side wall 6, wherein the second side wall 6 is designed as a locking cover, which is required for the axial locking, when the camshaft adjuster 1 in particular for the start of the engine in a middle position between "early" and "late" to be locked.

A chain, not shown, an operative connection between the crankshaft of the internal combustion engine and a drive gear is produced, which is rotatably connected to the outer rotor 4. An adjusting mechanism, not shown, establishes a relative rotational position between the outer rotor 4 and the inner rotor 3. The inner rotor 3 is rotatably screwed by a (not shown) central screw with the camshaft 2 of the internal combustion engine.

The two Figures 1 and 2 differ in that in the case of the solution according to the Fig. 1 the locking cover 6 is arranged on the side remote from the camshaft 2 side. Meanwhile, the lock cover 6 in the solution according to Fig. 2 positioned on the camshaft 2 facing side of the camshaft adjuster 1.

The locking cover 6 of the camshaft adjuster 1 can thus be located on the side facing the engine towards or away. Its axis is coaxial with the axis of the inner / outer rotor 3, 4 and the camshaft 2 aligned.

In Fig. 3 is the known per se construction of a generic camshaft adjuster 1 to see. In the exemplary embodiment, the outer rotor 4 has five incorporated recesses which form hydraulic chambers 7. These are by the two side walls 5, 6 (s. Fig. 1 and 2 ) limited.

In the inner rotor 3, five grooves are incorporated in the present embodiment, which in the present case in the radial direction and along the axial direction of the camshaft adjuster extend. In each groove, an element 8 is inserted in the form of a wing. The wing 8 extends in its assembled state radially to the outer radial boundary of the hydraulic chamber 7. Thus, the hydraulic chamber 7 is divided into two sub-chambers 9 and 10, which - not shown in detail - are in communication with hydraulic lines on the Hydraulic fluid in the sub-chambers 9, 10 can be initiated. The wing 8 can in principle also be designed as a sealing strip or similar element, which can accomplish a subdivision of the hydraulic chamber 7 into two sub-chambers 9, 10.

The locking of the camshaft adjuster 1 in a center position between "early" and "late" is accomplished by two locking pins 11 and 12, which are inserted into corresponding bores in the inner rotor 3. The locking pins are movable by means not shown in the axial direction and act as a locking piston. In conjunction with the design of the locking cover 6, a blockage of the relative rotation between the inner rotor 3 and outer rotor 4 can be made.

This is on the FIGS. 4 and 5 referenced, which show the locking cover 6 in cooperation with the inner rotor 3 and the outer rotor 4.

In the locking cover 6, two recesses 13 and 14 are incorporated, which act as scenes. They serve to define for the two locking pins 11 and 12 stop surfaces 15 and 16, which limit the recesses 13, 14 in the circumferential direction U, so that when locked locking pins 11, 12 of the inner rotor 3 relative to the outer rotor 4, on which the locking cover. 6 is attached, is set in the circumferential direction U, in a central position, as it is out Fig. 4 shows (the wings 8 are located approximately in the middle of the hydraulic chamber 7).

It is essential that at least one of the two recesses 13 and 14 - in the embodiment, both recesses 13, 14 - a stop surface 15, 16 for the locking pin 11, 12 such that their Position - viewed in the circumferential direction U - changed with the radial distance r from the axis 17 of the inner rotor 3. As can be seen, the two stop surfaces 15 and 16 formed here are arranged at an angle α to the radial direction R, which in the present case is approximately 15 °.

This results in the following advantageous effect: If the locking cover 6 is displaced relative to the outer rotor 4 in the radial direction R, a varying distance in the circumferential direction U results between the two stop surfaces 15 and 16 as a function of the radial relative position.

Referring to the embodiment according to Fig. 4 This means that with a radial displacement of the locking cover 6 relative to the outer rotor 4 outwardly with respect to the locking pins 11, 12 an increasing distance between the stop surfaces 15, 16 results, so that the play between the locking pins 11, 12 and the stop surfaces 15, 16 is growing. Conversely, this clearance is reduced when the lock cover 6 is displaced radially inwardly relative to the outer rotor 4.

In the embodiment according to Fig. 5 the two stop surfaces 15, 16 are reversely oriented. This means that here the play between locking pins 11, 12 and abutment surfaces 15, 16 decreases when the locking cover 6 is moved relative to the outer rotor 4 radially outward. Accordingly, it becomes larger when the lock cover 6 is moved radially inward.

This effect can be used to adjust the clearance between the locking pins 11, 12 and the abutment surfaces 15, 16 in the locking cover 6 during assembly of the camshaft adjuster.

A relative displacement of the locking cover 6 relative to the outer rotor 4 is in the embodiment according to the FIGS. 4 and 5 made possible by an embodiment of the possibility of attachment of the locking cover. 6 on the outer rotor 4, as indicated by the reference numerals 18 and 18 '. Here it can be seen that a bore 18, which is introduced for the passage of a fastening screw in the locking cover 6, meets a trained as a through hole counterbore 18 'in the outer rotor 4, which is formed larger and thus a radial displacement of the locking cover 6 relative to External rotor 4 allows.

The locking cover 6 is designed as a thin-walled disc. In the center of a circular recess 19 is provided, which allows the mounting of the camshaft adjuster to the engine by means of a central screw. The outer diameter of the locking cover 6 corresponds to that of the outer rotor. 4

The number of holes 18 in the locking cover 6 is dependent on the number of existing in the camshaft adjuster hydraulic chambers 7. The holes 18 may be formed as passage or threaded holes.

When the locking pins 11, 12 are actuated (for example by means of a spring force application in the axial direction), they enter the recesses 13, 14 and come into contact with each other Fig. 4 and 5 to be shown position. Then, a drive torque from the outer rotor 4 can be transmitted to the camshaft 2 via it.

The two abutment surfaces 15, 16 in the recesses 13, 14, which act as a backdrop, so act like a wedge over which the game can be adjusted.

During assembly, which also sets the locking clearance for the locking pins, proceed as follows:

When setting the locking game is - similar to the prior art locking in an end stop - the locking cover 6 positioned in the required position to the outer rotor 4 and then fixed.

When assembling the camshaft adjuster is initially locked completely pre-assembled, the screws for fixing the locking cover 6 are not yet tightened.

The outer rotor 4 (stator) is fixed in a mounting device. The inner rotor 3 is aligned in the outer rotor 4 with respect to the center locking position and also fixed.

Then, the lock cover 6 in the radial direction R (depending on the solution according to Fig. 4 or 5 inward or outward) until the play in the circumferential direction U between the locking pins 11, 12 and the abutment surfaces 15, 16 is zero.

To set a desired locking clearance of the locking cover 6 is then retracted by a corresponding amount in the radial direction R again (radially outward or inward) and then fixed with screws.

LIST OF REFERENCE NUMBERS

1

Camshaft adjustment device

2

camshaft

3

inner rotor

4

outer rotor

5

first sidewall

6

second side wall (locking cover)

7

hydraulic chamber

8th

Element (wing)

9

first compartment

10

second sub-chamber

11

locking pin

12

locking pin

13

Recess (backdrop)

14

Recess (backdrop)

15

stop surface

16

stop surface

17

axis

18, 18 '

drilling

19

recess

U

circumferentially

r

radial distance from the axis

R

radial direction

α

angle

Claims (8)

1. Device (1) for camshaft adjustment in an internal combustion engine, which device has an inner rotor (3) which is rotationally fixedly connected to a camshaft (2) and which can be adjusted in rotation relative to an outer rotor (4) which is drive-connected to a crankshaft, with at least one hydraulic chamber (7), which is bounded by side walls (5, 6), being formed in the outer rotor (4), with said hydraulic chamber (7) being divided into two sub-chambers (9, 10) by an element (8) which extends radially outward from the inner rotor (3), with two locking pins (11, 12) which extend axially through the inner rotor (3) being provided for locking the relative movement between the inner rotor (3) and outer rotor (4), which locking pins (11, 12) can engage into two recesses (13, 14) which are formed into one of the side walls (6) which is designed as a locking cover, and with at least one of the two recesses (13, 14) having a stop surface (15, 16) for the locking pin (11, 12), the position of which stop surface (15, 16) as viewed in the circumferential direction (U) varies with the radial distance (r) from the axis (17) of the inner rotor (3), characterized in that that side wall (6) of the device which is designed as a locking cover and the outer rotor (4) are designed such that the locking cover (6) can be fixed in different radial relative positions with respect to the outer rotor (4).
2. Device according to Claim 1, characterized in that the position of the two stop surfaces (15, 16) varies with the radial distance (r) from the axis (17) of the inner rotor (3).
3. Device according to Claim 1, characterized in that at least one stop surface (15, 16) has a straight profile.
4. Device according to Claim 3, characterized in that the at least one stop surface (15, 16) encloses an angle (α) with the radial direction (R).
5. Device according to Claim 3, characterized in that the stop surfaces (15, 16) are arranged such that their spacing as viewed in the circumferential direction (U) increases with increasing radial distance (r) from the axis (17) of the inner rotor (3).
6. Device according to Claim 3, characterized in that the stop surfaces (15, 16) are arranged such that their spacing as viewed in the circumferential direction (U) decreases with increasing radial distance (r) from the axis (17) of the inner rotor (3).
7. Device according to Claim 1, characterized in that bores (18, 18') for the leadthrough of fastening elements, in particular screws, are arranged in the locking cover (6) or in the outer rotor (4), which bores (18, 18') permit a radial movement between the locking cover (6) and the outer rotor (4).
8. Device according to Claim 1, characterized in that the locking cover (6) is of disk-shaped design.

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