DE102017115725A1 - Hydraulic camshaft adjuster - Google Patents

Abstract

The invention relates to a hydraulic camshaft adjuster (1) for adjusting the timing of gas exchange valves of an internal combustion engine, with a stator (2) which is rotatable synchronously with a crankshaft of the internal combustion engine, and a rotor (3) arranged rotatably relative to the stator (2) is rotatable synchronously with a camshaft, wherein on the stator (2) a plurality of webs (5) are provided, which divide an annular space (7) between the stator (2) and the rotor (3) in a plurality of pressure chambers (8). The rotor has (3) a rotor hub (4) and a plurality of vanes (6) extending radially outward from the rotor hub (4) and connecting the pressure chambers (8) into two groups, each with a pressure medium circuit. or working fluid chambers (9, 10) acted upon by downstream pressure medium with a different effective direction. The hydraulic camshaft adjuster (1) further has at least one locking link (12) in which a first locking pin (13) and a second locking pin (14) can fix the position of the rotor (3) relative to the stator (2). In this case, the first locking pin (13) is arranged in a first hydraulic inlet to the first group of working chambers (9) and the second locking pin (14) in a second hydraulic inlet to the second group of working chambers (10). The pressure medium supply of the working chambers (9, 10) is controlled by a central valve (22), wherein the locking pins (13, 14) are formed as stepped locking pins and release depending on their position, the pressure medium flow to the respective working chambers (9, 10) or The invention further relates to a method for controlling such a hydraulic camshaft adjuster (1), wherein the rotor (3) is rotated at an engine start from an arbitrary position into a center locking position.

Description

The invention relates to a hydraulic camshaft adjuster and a method for controlling a hydraulic camshaft adjuster according to the preamble of the independent claims.

Hydraulic camshaft adjusters are used in internal combustion engines to adjust a load state of the internal combustion engine and thus to increase the efficiency of the internal combustion engine. Hydraulic camshaft adjusters are known from the prior art, which operate on the vane principle. These camshaft adjusters generally have, in their basic construction, a stator which can be driven by a crankshaft of an internal combustion engine and a rotor connected in a rotationally fixed manner to the camshaft of the internal combustion engine. Between the stator and the rotor, an annular space is provided, which is divided by non-rotatably connected to the stator, radially inwardly projecting projections in a plurality of working chambers, which are each divided by a radially projecting from the rotor outwardly wings in two pressure chambers. Depending on the action of the pressure chambers with a hydraulic pressure medium, the position of the rotor relative to the stator and thus also the position of the camshaft with respect to the crankshaft in the direction of "early" or "late" can be adjusted. There are known hydraulic camshaft adjuster with a central locking, in which the rotor can be locked next to the respective end positions in a middle position, in particular to facilitate an engine start. In exceptional cases, for example in a stalling of the internal combustion engine, it is possible that the locking device does not lock the rotor as intended, and the camshaft adjuster must be operated in the subsequent starting phase with unlocked rotor. However, since some internal combustion engines have a very poor starting behavior when the rotor is not locked in the center position, the rotor must then be automatically rotated in the start phase in the center locked position and then locked.

Such independent rotation and locking of the rotor relative to the stator is out of the DE 10 2008 011 915 A1 known. The locking device described therein comprises a plurality of spring-loaded locking pins, which lock successively in a rotation of the rotor in provided on a sealing cover or the stator of the camshaft adjuster locking slot and allow before reaching the Mittenverrieglungsposition each rotation of the rotor in the direction of the center locking position, but a Block the rotation of the rotor in the opposite direction. After warming up of the internal combustion engine and / or the complete filling of the hydraulic camshaft adjuster with pressure medium, the locking pins are displaced by pressure medium actuated from the locking cams, so that the rotor can then be rotated as intended for adjusting the rotational angle position of the camshaft relative to the stator.

To lock the rotor relative to the stator, the pressure medium must first flow out of the locking slot into the pressure medium reservoir, so that the locking pins can engage in the gate. Furthermore, after stopping the internal combustion engine usually only a period of about 0.4 - 0.6 seconds remains until the final engine standstill. The locking of the rotor must therefore be completed in as short a time as possible, which can be problematic especially in the case of limited fluidity of the pressure medium, in particular at low temperatures and / or after a cold start of the internal combustion engine. Further, the pressure medium flow by means of a valve with a limited Magnetethub, which only releases a relatively small gap through which the pressure medium can flow. At a limited flowability of the pressure medium of the pressure medium flow can be reduced by the resistance generated in the gap but so far that the pressure medium can not escape quickly enough from the locking link.

From the EP 2 161 418 B1 is a hydraulic camshaft adjuster with a stepped locking pin known, which can be controlled by both pressure chambers. In this case, a connection to one of the pressure chambers can only be released when the locking pin is not in the locking position and a hydraulic connection to the corresponding pressure chamber is released.

The object of the invention is to provide a hydraulic camshaft adjuster with a central locking, which combines the advantages of a camshaft adjuster with integrated volume memory and the advantages of controlling the two locking pins and is characterized by a particularly simple and cost-effective production.

According to the invention, the object is achieved by a hydraulic camshaft adjuster for adjusting the timing of gas exchange valves of an internal combustion engine having a stator which is rotatable synchronously with a crankshaft of the internal combustion engine, and a rotatably arranged to the stator rotor, which is rotatable synchronously with a camshaft, solved, wherein the Stator a plurality of webs are provided which divide an annulus between the stator and the rotor in a plurality of pressure chambers, wherein the rotor has a rotor hub and a plurality of radially outwardly extending from the rotor hub wing, which the pressure chambers in two groups of each subdivide with a working in a pressure fluid circuit or flowing out pressure fluid working chambers with a different direction of action. Furthermore, the hydraulic phaser adjusts a central locking device for locking the rotor in a center locking position relative to the stator, wherein the center locking device has at least one locking link in which a first locking pin and a second locking pin can fix the position of the rotor relative to the stator. For this purpose, the first locking pin are arranged in a first hydraulic inlet to the first group of working chambers and the second locking pin in a second hydraulic inlet to the second group of working chambers. The pressure medium supply of the working chambers is controlled by a central valve. The locking pins are designed as stepped locking pins, wherein the locking pins release or block the pressure medium inflow to the working chambers as a function of their position. The proposed hydraulic camshaft adjuster, it is possible to rotate the stator after a start of the internal combustion engine from any position in the center locking position and thus to facilitate the engine start and the subsequent warm-up phase of the internal combustion engine. In this case, a self-regulated hydraulic freewheel is available, which supports the existing camshaft moments during rotation of the rotor from the start position to the center locking position. In addition, in the hydraulic camshaft adjuster according to the invention, a so-called C-channel, which is used in hydraulic camshaft adjusters known from the prior art for hydraulically unlocking the locking pins, can be omitted, so that fewer holes in the hydraulic camshaft adjuster are necessary.

The features listed in the dependent claims advantageous improvements and developments of the independent claim specified hydraulic camshaft adjuster are possible.

In a preferred embodiment of the invention, it is provided that the locking pins have a smaller pressure gauge in their stage facing the locking slot than at the stage facing away from the locking slot. In this case, the locking link facing stage when lifting from its seat release an oil supply channel to the respective working chambers, without additional valves or holes in the locking pins are necessary.

Further, in a further improvement of the invention that control edges are formed on at least a subset of the working chambers, wherein due to a combination of the position of the locking pins and the at least one control edge, a hydraulic freewheel of the hydraulic camshaft adjuster is controlled such that a central locking of the rotor possible is. By appropriate control edges, the corresponding working chambers can also be filled with concerns of the rotor blade on a web without additional effort, whereby the pressure medium flow to the respective working chambers can be facilitated.

It is particularly preferred if the locking pin for the adjustment of the rotor in the direction "early" locks in a release a control line to the control edge. By unlocking the locking pin a hydraulic connection is released to a group of working chambers, whereby a rotation of the rotor in the desired direction is made possible. In this case, the rotation can be facilitated in a center locking position by the corresponding opening of the hydraulic inlet to the working chamber, whereby the center locking position is reached faster.

In a further, advantageous improvement of the invention it is provided that the hydraulic camshaft adjuster has a reservoir for receiving pressure medium from the working chambers and for delivering pressure medium to the working chambers. By the reservoir can be ensured in an advantageous manner, the pressure medium supply of the working chambers of the hydraulic camshaft adjuster even if a supply of the corresponding working chamber alone by the pressure medium pump can not be guaranteed and would otherwise create a negative pressure in the corresponding pressure chambers. The corresponding pressure chambers then additionally suck in pressure medium from the reservoir, whereby higher adjustment speeds are possible. In addition, malfunctions and damage to the hydraulic camshaft adjuster can be avoided by the accumulator.

It is preferred if the reservoir is connected via a separate return line to a reservoir for storing the pressure medium. Through a separate return line, the supply channels to the pressure medium supply or for the discharge of pressure medium not by the in Reservoir located pressure fluid disturbed, so that the pressure medium can flow substantially unhindered from the working chambers when the pressure medium pump is turned off or the pressure medium supply to the working chambers is prevented by the central valve. As a result, the locking pins can sink unhindered into the locking slot, whereby a faster locking is possible.

According to a further improvement, it is provided that both the pressure medium supply of the working chambers and the locking or unlocking of the locking pins are controllable by the central valve. As a result, additional valves for controlling the pressure medium supply and disposal of the working chambers and / or the locking pins can be omitted, which reduces the cost of manufacturing and assembly.

According to a preferred embodiment of the invention it is provided that the locking pins are spring-loaded by the spring force of a spring. Spring-loaded locking pins ensure that the pins drop into the locking slot when there is a drop in pressure and lock the rotor in the center-locked position. Thus, in particular a subsequent restart of the internal combustion engine can be facilitated and it is ensured that the rotor does not remain in one of the adjustment positions.

In a preferred embodiment of the invention it is provided that the locking link is formed on a locking lid which limits the stator in the axial direction. By a lock in one of the covers a structurally comparatively simple locking link is possible, wherein the locking pins are displaceable in the axial direction under the influence of the pressure medium or the spring force.

According to the invention, a method for controlling a hydraulic camshaft adjuster according to the invention is proposed, in which the rotor is rotated at an engine start from an arbitrary position into a center locking position. By a corresponding hydraulic control of the locking pins after an engine start, a rotation of the rotor in a desired direction allows and a rotation against this direction can be locked. Thereby, the rotor can be rotated in a center locking position, which improves the smoothness and / or emissions of the internal combustion engine at a restart and a subsequent warm-up phase of the internal combustion engine. After this warm-up phase, in particular when the pressure medium has fallen below a defined threshold value of the viscosity, the hydraulic camshaft adjuster can then change the valve timing of the intake or exhaust valves of the internal combustion engine as intended.

The various embodiments of the invention mentioned in this application are, unless otherwise stated in the individual case, advantageously combinable with each other.

• 1 ein Ausführungsbeispiel eines erfindungsgemäßen hydraulischen Nockenwellenverstellers in einer abgewickelten Darstellung in einer Mittenverriegelungsposition;
• 2 den erfindungsgemäßen hydraulischen Nockenwellenversteller bei einem Start aus der Mittenverriegelungsposition;
• 3 den erfindungsgemäßen hydraulischen Nockenwellenversteller nach einem Start, wobei der Rotor zur Verstellung in eine entriegelte Position gebracht wird;
• 4 den erfindungsgemäßen hydraulischen Nockenwellenversteller bei einer Verdrehung des Rotors in Richtung „früh“;
• 5 den erfindungsgemäßen hydraulischen Nockenwellenversteller bei einer Verdrehung des Rotors in Richtung „spät“;
• 6 eine Verriegelung des Rotors eines erfindungsgemäßen hydraulischen Nockenwellenverstellers nach einem Motorstopp des Verbrennungsmotors in der „spät“-Position;
• 7 eine Verriegelung des Rotors eines erfindungsgemäßen hydraulischen Nockenwellenverstellers nach einem Motorstopp des Verbrennungsmotors in der „früh“-Position.

The invention will be explained in more detail below by a preferred embodiment and the accompanying drawings. The same components or components with the same function are identified by the same reference numerals. Show it:

• 1 an embodiment of a hydraulic camshaft adjuster according to the invention in a developed view in a center locking position;
• 2 the hydraulic phaser according to the invention at a start from the center locking position;
• 3 the hydraulic phaser according to the invention after a start, wherein the rotor is brought into an unlocked position for adjustment;
• 4 the hydraulic camshaft adjuster according to the invention in a rotation of the rotor in the direction "early";
• 5 the hydraulic camshaft adjuster according to the invention with a rotation of the rotor in the direction of "late";
• 6 a locking of the rotor of a hydraulic camshaft adjuster according to the invention after an engine stop of the internal combustion engine in the "late"position;
• 7 a locking of the rotor of a hydraulic camshaft adjuster according to the invention after an engine stop of the internal combustion engine in the "early" position.

In 1 is an embodiment of a hydraulic camshaft adjuster according to the invention 1 shown for adjusting the valve timing of an internal combustion engine. The in 1 schematically illustrated hydraulic camshaft adjuster 1 is formed in a known manner as Flügelzellenversteller and includes a drivable by a crankshaft, not shown, of an internal combustion engine stator 2 and a rotatably connected to a camshaft, also not shown rotor 3 , The rotor 3 has a rotor hub 4 on, from which in the radial direction several wings 6 extend. In the illustration shown is the hydraulic camshaft adjuster 1 shown in a development, while additionally a section of the rotor hub 4 with a center locking device 11 as well as a central valve 22 and a reservoir 16 for controlling the pressure medium supply of the hydraulic camshaft adjuster 1 are shown.

The stator 2 has a plurality of webs 5 on which an annulus 7 between the stator 2 and the rotor 3 in several pressure chambers 8th divide. The pressure chambers 8th be through the wings 6 of the rotor 3 each in two working chambers 9 . 10 divided with different effective direction. The center locking device 11 includes two locking pins 13 . 14 , which for locking the rotor 3 opposite the stator 2 in a locking frame 12 are lockable. The locking pins 13 . 14 are in the rotor 3 slidably mounted and each by a spring 23 loaded. The locking mechanism 12 is preferably in a locking lid, not shown, of the hydraulic camshaft adjuster 1 formed, which the stator 2 limited in the axial direction, but may alternatively also in the stator 2 be self-trained.

In principle, the angle of rotation of the camshaft to the crankshaft in normal operation of the hydraulic camshaft adjuster 1 thereby displaced by having a first group of working chambers 9 be acted upon with pressure medium and thereby increase their volume, while at the same time the pressure medium from a second group of working chambers 10 displaced and their volume is reduced. The working chambers 9 , whose volume is increased in groups in each case during this adjustment, are in the context of the invention as working chambers 9 denotes a direction of action, while the working chambers 10 whose volume is simultaneously reduced, as working chambers 10 be designated the opposite direction of action. The increase in volume of the working chambers 9 causes the rotor 3 opposite the stator 2 is twisted in the direction of "early". The corresponding pressure medium supply of the working chambers 9 , is carried out by a pressure medium pump 17 from a storage container 18 ,

In 1 is the hydraulic camshaft adjuster 1 in a center locking position, wherein the hydraulic phaser 1 without a hydraulic pressure of the pressure medium pump 17 is shown. Here is the central valve 22 , which is preferably designed as a 4/4-way valve, in a first switching position. Here are the working chambers 9 . 10 with the reservoir 16 connected so that the hydraulic pressure in the working chambers 9 . 10 can be reduced. The two locking pins 13 . 14 are in the locking slot 12 locked and the wings 6 of the rotor 3 , each as a stepped locking pins 13 . 14 are executed, are in the center locking position. In 1 is schematically a hydraulic phaser 1 with three pressure chambers 8th and three wings 6 on the rotor 3 illustrated, in principle, the hydraulic camshaft adjuster 1 also more than three pressure chambers 8th and the rotor 3 correspondingly more wings 6 exhibit.

In 2 is the hydraulic camshaft adjuster according to the invention 1 shown at a start of the internal combustion engine from the center locking position. In the de-energized state of an actuator for the central valve 22 located are the central valve 22 in the in 1 shown first switching position. With start of the internal combustion engine becomes the central valve 22 placed in a second switching position, in which the pressure medium pump 17 via a first pressure medium supply channel 20 , hereinafter also referred to as B-channel, with the working chambers 10 and a switch room for unlocking the second locking pin 14 connected is. Through the first locking pin 13 is a hydraulic connection with the working chamber B2 still locked. By unlocking the second locking pin 14 can the pressure fluid from the working chambers 9 drain in the direction of the reservoir. In this state is the rotor 3 through the first locking pin 13 and the hydraulic pressure in the working chambers 10 hydraulically braced and allows no change in position of the rotor 3 so that it remains in the center position.

A first change of position of the rotor 3 after the engine start of the internal combustion engine is only by adjusting the central valve 22 in a fourth shift position possible. As in 3 shown, causes the adjustment of the central valve 22 a hydraulic connection of the pressure medium pump 17 via a first pressure medium supply channel 19 , which is also referred to below as the A-channel 19, with the first group of working chambers 9 , The second group of working chambers 10 is via the central valve 22 with the reservoir 16 connected, so that excess pressure fluid from the second group of working chambers 10 in the reservoir 16 can drain away. The reservoir 16 is also via a separate return line 21 with the reservoir 18 connected, so that excess pressure fluid from the reservoir 18 can drain without the function of the hydraulic camshaft adjuster 1 to influence. In this operating state, an adjustment of the rotor in the direction of "early" is possible for the first time. Such an adjustment is in 4 shown.

In 4 is an adjustment of the rotor 3 in the direction of "early". In this state, the hydraulic camshaft adjuster works 1 like the known from the prior art camshaft adjuster. With an actuation of the central valve 22 the adjustment direction is controlled. In the second switching position of the central valve 22 an adjustment is directed towards "late" while in the fourth shift position, an adjustment in the direction of "early" is controlled. The locking pins 13 . 14 are designed as stepped pins and are held by the step function with pressure. In addition, they would be unlocked at a possible pressure drop in the step chamber by the unlocking function again.

5 shows an adjustment of the rotor 3 in the direction of "late". The pressure medium supply is in normal operation in a known manner by the pressure medium pump 17 or additionally through the reservoir 16 possible. In a start / stop situation, especially in a scheduled stop of the engine, the rotor 3 of the hydraulic camshaft adjuster 1 be rotated in the center locking position and by the pressure shutdown of the pressure medium pump 17 in this center locking position by means of the two locking pins 13 . 14 be locked.

As experience shows, there are situations in which the hydraulic camshaft adjuster 1 no longer had the opportunity to use the rotor 3 to rotate in the center locking position at an engine stop of the internal combustion engine is in the hydraulic camshaft adjuster according to the invention 1 considered the possibility of adjustment from any position in the center locking position. In 6 is shown an engine start situation in which the rotor 3 is rotated from an adjustment position in the direction of "late" in the center locking position. The initial condition now is that the first locking pin 13 positive fit from the locking link 12 unlocked and the second locking pin 24 in a slot of the locking link 12 remains locked. An unlocking of the second locking pin 14 can only take place when the rotor 3 was rotated in the center locking position and is hydraulically supported in this. By locking the second locking pin 14 in the slot of the locking link 12 is a hydraulic connection to a control edge 15 at one of the working chambers 9 . 10 Approved. This hydraulic connection is guaranteed until reaching the center locking position. Due to the initial situation of the rotor 3 in the "late" position becomes the control edge 15 through the wing 7 of the rotor 3 obscured, leaving a pressure in the working chamber 9 arises. This hydraulic pressure allows adjustment of the rotor 3 in the center locking position.

In 7 is shown a starting situation of the internal combustion engine when the rotor 3 from a previous operation is still in an "early" position. This is the central valve 22 first in the first switching position in which the working chambers 9 . 10 with the reservoir 16 are connected and initially no pressure in the working chambers 9 . 10 can be built. By connecting to the reservoir 16 the working chamber B2 is supplied with pressure medium from the reservoir, so that at an enlargement of the working chambers 10 no air is sucked in. That in the working chambers 9 located fluid can through the A-channel 19 in the reservoir 16 flow away. In this case, the second locking pin 24 is a drain from the working chambers 9 in the direction of the reservoir 16 free. The first locking pin 13 blocks a drain from the working chamber B2, so that the pressure medium can not flow and is caused by the alternating moments of the camshaft an adjustment in the direction of the center locking position. Furthermore, the first locking pin locks 13 a rotation of the rotor 3 against rotation in the center locking position. An unlocking of the first locking pin 13 can only take place when the rotor 3 was rotated in the center locking position and is hydraulically supported in this. This is the central valve 22 placed in the second switching position and the rotor 3 hydraulically turned into the center locking position. Once both locking pins 13 . 14 unlocked, the rotor can 3 by a corresponding switching position of the central valve 22 and a corresponding pressure medium supply of the working chambers 9 . 10 be adjusted via the A-channel 19 and the B-channel 20 in the direction of "early" or "late", so that the opening times of the gas exchange valves can be adapted to the respective operating condition of the internal combustion engine.

In a hydraulic camshaft adjuster according to the invention, it is thus possible to rotate the rotor from any starting position to the center locking position.

LIST OF REFERENCE NUMBERS

1

hydraulic camshaft adjuster

2

stator

3

rotor

4

rotor hub

5

web

6

wing

7

annulus

8th

pressure chamber

9

working chamber

10

working chamber

11

Center locking device

12

locking link

13

first locking pin

14

second locking pin

15

control edge

16

reservoir

17

Hydraulic pump

18

reservoir

19

A channel

20

B-channel

21

Return line

22

central valve

23

feather

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008011915 A1 [0003]
• EP 2161418 B1 [0005]

Claims (10)

Hydraulic camshaft adjuster (1) for adjusting the timing of gas exchange valves of an internal combustion engine, comprising - a stator (2) which is rotatable in synchronism with a crankshaft of the internal combustion engine, and - a rotatable to the stator (2) arranged rotor (3) which synchronously with a camshaft is rotatable, - on the stator (2) a plurality of webs (5) are provided, which divide an annular space (7) between the stator (2) and the rotor (3) in a plurality of pressure chambers (8) - The rotor (3) has a rotor hub (4) and a plurality of from the rotor hub (4) radially outwardly extending wings (6) which the pressure chambers (8) in two groups each with a in a pressure medium circuit or subordinate pressure working fluid (9, 10) with a different effective direction, and - the hydraulic camshaft adjuster (1) at least one locking link (12), in which a first locking pin (13) and a second locking pin (14) can fix the position of the rotor (3) relative to the stator (2), and wherein - the first locking pin (13) in a first hydraulic inlet to the first group of working chambers (9 ) and the second locking pin (14) is arranged in a second hydraulic inlet to the second group of working chambers (10), characterized in that - the pressure medium supply of the working chambers (9, 10) is controlled by a central valve (22), and wherein - The locking pins (13, 14) are formed as stepped locking pins, wherein the locking pins (13, 14) depending on their position, the pressure medium flow to the working chambers (9, 10) enable or disable. Hydraulic camshaft adjuster (1) to Claim 1 , characterized in that the locking pins (13, 14) in their the locking slide (12) facing the stage have a smaller diameter than at its side facing away from the locking link stage. Hydraulic camshaft adjuster (1) to Claim 1 or 2 , characterized in that on at least a subset of the working chambers (9, 10) control edges (15) are formed, wherein due to a combination of the position of the locking pins (13, 14) and the at least one control edge (15), a hydraulic freewheel of the hydraulic camshaft adjuster (1) is controlled such that a center locking of the rotor (3) is possible. Hydraulic camshaft adjuster (1) to Claim 3 , characterized in that the locking pin (13) for the adjustment of the rotor (3) in the direction "early" when unlocking a control line to the control edge (15) blocks. Hydraulic camshaft adjuster (1) according to one of Claims 1 to 4 , characterized in that the hydraulic camshaft adjuster (1) has a reservoir (16) for receiving pressure medium from the working chambers (9, 10) and for delivering pressure medium to the working chambers (9, 10). Hydraulic camshaft adjuster (1) to Claim 5 , characterized in that the reservoir (16) via a separate return line (21) with a reservoir (18) is connected to the storage of the pressure medium. Hydraulic camshaft adjuster (1) according to one of Claims 1 to 6 , characterized in that both the pressure medium supply of the working chambers (9, 10) and the locking or unlocking of the locking pins (13, 14) in the locking link (12) by the central valve (22) are controllable. Hydraulic camshaft adjuster (1) according to one of Claims 1 to 7 , characterized in that the locking pins (13, 14) are spring loaded by the spring force of a spring (23). Hydraulic camshaft adjuster (1) according to one of Claims 1 to 8th , characterized in that the locking link (12) on a locking cover of the hydraulic camshaft adjuster (1) is formed, which limits the stator (2) in the axial direction. Method for controlling a hydraulic camshaft adjuster (1) according to one of Claims 1 to 9 , characterized in that the rotor (3) is rotated at an engine start from an arbitrary position to a center locking position.

Images