Hydraulic camshaft phaser for variable valve control of internal combustion engine and method for operating hydraulic camshaft phaser

Abstract

The invention relates to a hydraulic camshaft phaser for variable valve control of an internal combustion engine, comprising a stator (1) and a rotor (2) and a plurality of pressure chambers (3) which are delimited by the stator and the rotor and into which a pressure medium can be introduced, the invention relates to an internal combustion engine comprising a stator (1) and a rotor (2) for adjusting the relative angular phase position of rotation between the stator (1) and the rotor (2), characterized in that at least one pressure medium outflow connection (11, 12, 28, 29) to the surroundings is provided such that, in the angular phase position of rotation for the maximum delay valve control time of the internal combustion engine, the pressure medium outflow connection (11, 12, 28, 29) is connected to the surroundings. The pressure medium flows out of the at least one pressure chamber (3) into the surroundings due to the action of gravity during the engine rest of the internal combustion engine, which pressure medium outflow connection can be closed again during the engine start-up by adjusting the relative rotational angle phase position. The invention also relates to a method for operating a hydraulic camshaft phaser of this type.

Description

Technical Field

[0001] The invention relates to a hydraulic camshaft phaser for variable valve control of an internal combustion engine of the type defined in more detail in the preamble to claim 1. The invention also relates to a method for operating a hydraulic camshaft phaser of this type. Background Art

[0002] DE 10 2019 119 865 B4 discloses a hydraulic camshaft phaser for a drive train of a motor vehicle, comprising a stator and a rotor rotatable relative to the stator, wherein a working chamber is formed between the stator and the rotor, into which a hydraulic fluid can be introduced in order to adjust the rotor relative to the stator. Summary of the Invention

[0003] The present invention is therefore based on the object of proposing a hydraulic camshaft phaser and a method of the aforementioned type which can improve the hydraulic camshaft phasing during engine starting of an internal combustion engine in a structurally simple manner and in particular avoid disturbances due to noise and vibrations.

[0004] This object is achieved by the features of claim 1 and, alternatively, by the features of claim 10. Further advantageous and claimed embodiments emerge from the corresponding dependent claims, the description and the drawings.

[0005] Therefore, a hydraulic camshaft phaser for variable valve control of an internal combustion engine is proposed. The hydraulic camshaft phaser includes a stator and a rotor, and a plurality of pressure chambers delimited by the stator and rotor. A pressure medium can be introduced into the pressure chambers to adjust the relative rotational angle phase position between the stator and the rotor, thereby enabling valve control timing of the internal combustion engine. At least one pressure medium outflow connection to the surrounding environment is provided, so that in a rotational angle phase position of the camshaft phaser for enabling maximum retarded valve control timing, pressure medium flows from the at least one pressure chamber to the surrounding environment due to gravity during engine standstill of the internal combustion engine. The pressure medium outflow connection can be closed again during engine startup by adjusting the relative rotational angle phase position.

[0006] By displacing pressure medium from the pressure chamber during engine standstill, damping can be significantly reduced or even completely eliminated when adjusting to an earlier valve control time during engine startup. This enables a very rapid adjustment of the rotational angle phase position to an earlier valve control time, even during engine startup and when the required pressure medium pressure is not available, solely due to the dynamically alternating torques acting on the camshaft of the internal combustion engine during operation and the frictional forces generated during operation.

[0007] In a particularly advantageous manner, during engine starting from engine standstill with maximum delayed valve control times, a short-term decompression of the internal combustion engine can be achieved and disturbances caused by noise and vibration, i.e. noise vibration harshness (NVH) problems, can be reliably avoided.

[0008] In a particularly simple embodiment of the present invention, the pressure medium outflow connection comprises at least one first pressure medium outflow channel on the stator, which extends from the outer diameter to at least one bearing surface on the inner diameter. Preferably, at least one second pressure medium outflow channel is arranged on the outer diameter of the rotor such that, when the engine is stationary, it communicates with the pressure chamber on the one hand and with the first pressure medium outflow channel on the other hand. This allows a direct pressure medium outflow connection between the at least one pressure chamber and the surrounding environment when the engine is stationary.

[0009] If the first pressure outlet channel and the second pressure outlet channel are arranged so that, by adjusting the relative rotational angle phase position, the first pressure medium outflow channel can be covered by the outer diameter of the rotor in a pressure-tight manner, and the second pressure medium outflow channel can be covered by the supporting surface on the inner diameter of the stator in a pressure-tight manner, a simple closing of the pressure medium outflow connection can be achieved during engine startup.

[0010] By designing the first pressure medium outflow channel as a radial through hole on the stator and the second pressure medium outflow channel on the outer diameter of the rotor as a radial recess extending in an arc shape in the circumferential direction, preferably an elbow groove, the pressure medium outflow connection can be further simplified in terms of construction.

[0011] The elbow groove can be arranged in a simple manner such that during engine standstill, a first end in the region of the stator's bearing surface communicates with the through-hole and a free second end extending outside the region of the bearing surface communicates with the pressure chamber.

[0012] In a design optimized for pressure medium outflow during engine starting and engine standstill, the elbow recess extends through the free second end, outside the area of ​​the bearing surface, by a predetermined elbow length in the direction of adjusting the relative rotational angle phase position relative to engine starting. Preferably, this elbow length corresponds to an adjustment of the relative rotational angle phase position by 1° to 2° during engine starting. This means that during engine starting, by adjusting the relative rotational angle phase position toward an earlier valve control time, the pressure medium outflow connection can be interrupted or closed as soon as an adjustment of 1° to 2° away from the maximum retarded position is achieved.

[0013] The pressure medium outflow connection can be further optimized in a simple manner by adapting the radial depth of the elbow recesses on the rotor and the diameter of the radial through-holes on the stator to the use and operating conditions of the camshaft phaser. To optimize the desired pressure medium outflow, the operating conditions during normal operation of the internal combustion engine, in particular the operating temperature when the engine is hot, are preferably used as a basis.

[0014] It is also advantageous if at least two pressure medium outflow connections to the surroundings, which are arranged diametrically opposite one another on the stator and / or the rotor, are arranged such that, during an engine standstill of the internal combustion engine, pressure medium flows out of the at least two pressure chambers arranged diametrically opposite one another on the stator and / or the rotor into the surroundings due to gravity. In this way, the pressure medium outflow connections can be positioned in the effective direction of gravity during an engine standstill, so that one pressure medium outflow connection is arranged at the bottom in the effective direction of gravity for discharging pressure medium, and the other pressure medium outflow connection, which is arranged diametrically opposite one another, is arranged at the top in the effective direction of gravity for ventilating the pressure chamber or letting air into the pressure chamber during pressure medium outflow.

[0015] It is advantageous if at least two first pressure medium channels arranged diametrically opposite one another in the region of the stator's bearing surface are arranged aligned as radial through-holes. The through-holes can thus be positioned in the effective direction of gravity when the engine is stationary.

[0016] Preferably, at least two first pressure medium outflow channels are provided, arranged diametrically opposite one another in the region of the stator's bearing surface and designed as radial through-holes, and at least two second pressure medium outflow channels are arranged diametrically opposite one another on the rotor and designed as radial elbow grooves extending in the circumferential direction on the outer diameter. The respective first and second pressure medium outflow channels are connected in the manner described above when the engine is stationary and can be closed again in the manner described above during engine startup.

[0017] In an advantageous refinement of the present invention, at least two pairs of pressure medium outflow connections to the surroundings, arranged diametrically opposite one another on the stator and / or rotor, are configured such that, during engine standstill of the internal combustion engine, pressure medium flows out of the at least two pairs of pressure chambers, arranged diametrically opposite one another on the stator and / or rotor, into the surroundings due to gravity. Thus, at least four pressure chambers of the camshaft phaser can be directly connected to the surroundings for gravity-induced pressure medium outflow during engine standstill and can be closed again in a pressure-tight manner during engine startup. This design optimizes the gravity-induced pressure medium outflow from the pressure chambers in any engine standstill position.

[0018] Preferably, two pairs of two first pressure medium outflow channels are arranged diametrically opposite one another in the region of the stator's bearing surface and are designed as radial through-holes, and at least two pairs of two second pressure medium outflow channels are arranged diametrically opposite one another on the rotor and are designed as radial elbow grooves extending in the circumferential direction on the outer diameter. The respective first and second pressure medium outflow channels are connected in the manner described above when the engine is stationary and can be closed again in the manner described above during engine startup.

[0019] The above-described camshaft phaser is particularly advantageous for use in vehicles with a hybrid drive, wherein the internal combustion engine can be started very quickly by the electric motor of the hybrid drive and can be easily returned to a defined rest position.

[0020] The objects of the present invention are also achieved by a method for operating a hydraulic camshaft phaser as described above, wherein the camshaft phaser is moved from a maximum retard adjustment position for enabling a maximum retard valve control time when the internal combustion engine is at a standstill to a central adjustment position between the maximum retard adjustment position and the maximum advance adjustment position for controlling a maximum advance valve control time in a time of less than one second during engine starting of the internal combustion engine by the action of an alternating torque generated on a camshaft of the internal combustion engine during operation to operate the internal combustion engine.

[0021] In this way, by delaying the valve control timing during engine startup while the engine is stationary, the intake gas exchange valve of the internal combustion engine can be kept open for a short period of time, and a short-term decompression of the internal combustion engine can be achieved. By quickly adjusting the valve control timing to an earlier valve control timing during operation by means of the alternating torque acting on the camshaft, the aforementioned disturbances in the internal combustion engine caused by noise and vibration during engine startup can be avoided.

[0022] Preferably, during engine standstill of the internal combustion engine, pressure medium is at least partially released from the hydraulic pressure chamber into the surroundings due to gravity, thereby avoiding or at least reducing damping caused by pressure medium displaced from the pressure chamber during adjustment to an earlier valve control time.

[0023] Furthermore, when the internal combustion engine is at a standstill, the camshaft phaser can be brought into a defined parking position by the method described above, so that at least one pressure medium outflow connection provided for pressure medium outflow is aligned in the effective direction of gravity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other claimed features of the invention are apparent from the following description and the accompanying drawings, based on which the invention is explained in more detail. In the accompanying drawings:

[0025] Figure 1 A hydraulic camshaft phaser for variable valve control of an internal combustion engine according to a first exemplary embodiment of the present invention is shown in an exploded view.

[0026] Figure 2 A hydraulic camshaft phaser is shown in a side cross-sectional view in an operating state during engine standstill of an internal combustion engine,

[0027] Figure 3 Shown Figure 2 An enlarged cross-sectional view of

[0028] Figure 4 A hydraulic camshaft phaser for variable valve control of an internal combustion engine according to a second exemplary embodiment of the present invention is shown in a side sectional view in an operating state during engine standstill of the internal combustion engine. DETAILED DESCRIPTION

[0029] The accompanying drawings show various views and embodiments of a hydraulic camshaft phaser for variable valve control of an internal combustion engine according to the present invention. The figures also illustrate the method according to the present invention.

[0030] The hydraulic camshaft phaser comprises a stator 1 which can be driven to rotate about a rotational and central axis 27 and a rotor 2 which can be rigidly coupled to a camshaft (not shown) ( Figure 1 and Figure 2 ). The stator 1 can be driven by the crankshaft (not shown) of the internal combustion engine via a drive wheel 35, here a sprocket, which is arranged coaxially with the stator and is connected to the stator in a rotationally fixed manner via a threaded connection 34. The inner diameter or inner circumference of the stator is coaxially supported on the outer diameter or outer circumference of the rotor 2. The stator 1 and the rotor 2 are arranged to be rotatable relative to each other so that the relative rotational angle phase position between the stator and the rotor can be adjusted in two effective directions of the camshaft phaser to enable the valve control timing of the internal combustion engine. The stator and the rotor define a plurality of pressure chambers 3, four pressure chambers as an example, which are arranged one after another in the rotational direction or circumferential direction, and pressure medium can be introduced into the pressure chambers to adjust the relative rotational angle phase position of the stator 1 and the rotor 2. The pressure chambers 3 are arranged in pairs on the stator 1 and the rotor, diametrically opposite each other. The pressure medium used is preferably oil from an oil circuit, preferably from a reservoir in the engine oil circuit of the internal combustion engine.

[0031] In order to adjust the relative rotational angular phase position, four vanes 4 ( Figure 1 and Figure 2). The vanes 4 can be supplied with pressure medium in the corresponding pressure chambers 3 on both sides of the rotational direction through openings 5 ​​and 6 on the outer diameter of the rotor 2. By supplying pressure medium to the vanes 4 and releasing the pressure medium accordingly, the vanes can rotate oppositely in the pressure chambers with the rotor 2 relative to the stator 1 in both rotational directions. By adjusting the relative rotational angular phase position between the stator 1 and the rotor 2, the camshaft of the internal combustion engine can be adjusted toward a later or earlier valve control time for opening or closing the gas exchange valves (not shown) of the internal combustion engine.

[0032] Rotating the rotor 2 counterclockwise relative to the stator 1 allows the relative rotational angle phase position to be adjusted toward a later valve control timing, while rotating the rotor 2 clockwise relative to the stator 1 allows the relative rotational angle phase position to be adjusted toward an earlier valve control timing. Adjustment of the relative rotational angle phase position is limited to a maximum retarded position toward a later valve control timing by a retarding stop 7, and to a maximum advanced position toward an earlier valve control timing by an advancing stop 8. The vanes 4 can be positioned against the stops 7 and 8 in either the rotational or circumferential direction to limit adjustment. Each vane is disposed in two pressure chambers 3 diametrically opposed to each other on the rotor 2 and stator 1.

[0033] The stops 7 and 8 are each formed on the radially inwardly projecting web 9 of the stator 1 on a side of the web 9 that is aligned in the circumferential or rotational direction. The web 9 delimits the pressure chamber 3 in the rotational and circumferential directions. The web forms a bearing surface 10 radially inwardly on its inner diameter, via which the stator 1 rests on the outer diameter of the rotor 2. The pressure chamber 3 is radially delimited outward by the stator 1 and inward by the outer diameter of the rotor 2. Radial sealing elements 36 may be provided on the bearing surface 10 of the stator 1 and on the radial end faces of the free ends of the blades 4 for pressure-tight sealing.

[0034] Figure 1 and Figure 2 A camshaft phaser in a first exemplary embodiment is shown. Figure 2 The camshaft phaser of an internal combustion engine is shown during engine standstill, wherein the stator 1 and the rotor 2 are set in a relative rotational angle phase position that is in a maximum retarded position. The vanes 4 are positioned in the pressure chamber 3 at respective retarded stops 7 in the rotational or circumferential direction.

[0035] Two pressure medium outflow connections 11, 12 to the surroundings are provided which are arranged diametrically opposite one another so that the pressure medium flows out of two pressure chambers 3 which are arranged diametrically opposite one another on the stator 1 and / or the rotor 2 due to gravity during an engine stop of the internal combustion engine. The pressure medium outflow connections each comprise a first pressure medium outflow channel 13, 14 which extends between the outer diameter and the inner diameter of the stator 1 in the region of the support surface 10 and a second pressure medium outflow channel 15, 16 which is arranged on the outer diameter of the rotor 2. The first pressure medium outflow channels 13, 14 and the second pressure medium outflow channels 15, 16 are arranged diametrically opposite one another on the stator 1 and the rotor 2, respectively. This is indicated by a dot-dash line and a hidden body edge is indicated by a dashed line ( Figure 1 ).

[0036] The first pressure medium outflow channels 13 and 14 are each designed as radial through-holes in the web 9 of the stator 1 and are arranged diametrically opposite one another. The second pressure medium outflow channels 15 and 16 are formed by radial recesses that extend in a curved manner in the circumferential direction on the outer diameter of the rotor 2 and are each designed as an elbow groove. The first pressure medium outflow channels or radial through-holes 13 and 14 are each arranged in the circumferential direction or rotational direction in the region of the early stop 8 of the corresponding web 9 on the stator 1.

[0037] according to Figure 2 and Figure 3 , the first pressure medium outflow channels or radial through-holes 13, 14 and the second pressure medium outflow channels or elbow grooves 15, 16 are arranged so that during engine standstill, the elbow grooves 15, 16 on the outer diameter of the rotor 2 are each connected in the circumferential direction via a first end 17, 18 in the region of the bearing surface 10 of the stator 1 with the corresponding through-hole 13, 14 and via a free second end 19, 20 in the region of the early stop 8 with the corresponding pressure chamber 3 ( Figure 3 In this way, during engine standstill, in the maximum retarded position 7, pressure medium from the region of the pressure chamber 3 which is located on the side of the vane 4 arranged in the adjustment direction during engine start-up in the advance direction and which is reduced during adjustment can be completely discharged to the surroundings via the pressure medium outflow connections 11, 12.

[0038] The through holes 13, 14 on the inner diameter of the stator 1 and the elbow grooves 15, 16 on the outer diameter of the rotor 2 are arranged at the same axial height X, so that the through holes 13, 14 are respectively radially opposite to the elbow grooves 15, 16 in the relative rotational angle phase position during engine standstill and are connected to the elbow grooves for pressure medium outflow.

[0039] Here, the following free second ends 19, 20 of the elbow grooves 15, 16 are arranged outside the area of ​​the supporting surface 10 and are exposed to communicate with the pressure chamber 3: the free second ends have a predetermined elbow length S in the circumferential direction or counterclockwise direction for adjusting the relative rotational angle phase position for engine start-up, that is, in the direction of adjusting to an earlier valve control time.

[0040] Thus, when the engine is stationary, the pressure medium can flow directly from the pressure chamber 3 due to gravity through the free ends of the elbow grooves 15, 16 communicating with the pressure chamber and also through the through-holes 13, 14 communicating with the elbow grooves into the surrounding environment. In this way, when the engine is stationary, the direct pressure medium outflow connections 11, 12 serve to a certain extent as a short circuit between the pressure chamber 3 and the surrounding environment for the outflow of the pressure medium.

[0041] Depending on the positioning of the through-holes 13 , 14 during engine standstill, one of the through-holes 13 , 14 serves for pressure medium outflow, while the other through-hole 13 , 14 serves for venting the pressure chamber 3 or for admitting air into the pressure chamber during pressure medium outflow, as indicated by the arrows.

[0042] The outflow of pressure medium can also be achieved during engine standstill due to gravity from the pressure chambers 3 which are not in direct communication with the surroundings via the pressure medium outflow connections 11, 12, since these pressure chambers 3 are pressure-medium connected via openings 5, 6 on the outer diameter of the rotor 2 to the central annular channel 21 in the region of the central through-opening 22 on the rotor 2 and via the annular channel 21 to the pressure chambers 3 which are directly connected to the pressure medium outflow connections 11, 12 ( Figure 1 and Figure 2 A central hydraulic control valve (not shown) for hydraulically controlling the camshaft phaser can be inserted into a central through-opening 22 on the rotor 2 .

[0043] In order to optimize the required pressure medium outflow, the design of the pressure medium outflow connections 11, 12 can be further optimized by adapting the radial depth T of the elbow recesses 15, 16 on the rotor 2 and / or the diameter D of the radial through holes 13, 14 on the stator 1 to the use and operating conditions of the camshaft phaser. Figure 3 ). Preference is given to using the operating conditions during normal operation of the internal combustion engine, in particular the operating temperature when the engine is hot, as a basis.

[0044] Since the pressure medium is at least partially discharged from the pressure chamber 3 via the pressure medium outflow connections 11, 12 during engine standstill, the damping of the pressure medium discharged from the pressure chamber 3 during adjustment towards an earlier valve control time in the event of an engine start is reduced to such an extent that if the pressure medium pressure is insufficient during engine start, adjustment can only be performed by the alternating torque of the camshaft acting on the rotor 2 during operation. This also makes it possible to overcome friction that would otherwise hinder adjustment towards an earlier valve control time.

[0045] A torsion spring device (not shown) arranged between the stator 1 and the rotor 2 can also be provided to assist in adjustment in the direction of an earlier valve control time during engine startup, and the torsion spring device pre-tensions the stator 1 and the rotor 2 to adjust the relative rotational angle phase position in the direction of an earlier valve control time.

[0046] Preferably, if Figure 2 and Figure 3 As shown, during the engine standstill, the first pressure medium outflow channels or through-holes 13, 14 are arranged along the effective direction of gravity 23 indicated by the arrow ( Figure 2 The through-hole 14 and the second pressure medium outflow channel or the elbow groove 16, which are located at the bottom relative to the effective direction of gravity 23, serve to allow the pressure medium to flow out directly into the surrounding environment, while the through-hole 13 and the elbow groove 15, which are located at the top relative to the effective direction of gravity 23, ventilate the pressure chamber 3 during the pressure medium outflow. In this way, an optimal pressure medium outflow can be achieved when the internal combustion engine is at a standstill.

[0047] Preferably, a locking mechanism 24 is provided, by means of which the stator 1 and the rotor 2 can be coupled in a rotationally rigid manner in certain operating states, such as when the internal combustion engine is at a standstill. Figure 2 and 3 Preferably, the locking mechanism 24 is designed and the camshaft phaser is arranged on the camshaft in the assembled state so that when the engine is stationary and the position of the stator 1 and the rotor 2 is locked in the maximum retarded position 7, the pressure medium outflow connections 11, 12 are aligned in the effective direction of gravity 23 as described above ( Figure 2 In order to lock the stator 1 and the rotor 2, the locking mechanism 24 has a plurality of locking pins 26 arranged in holes pre-tensioned by springs 25, which can be displaced by a pressure medium ( Figure 1 ).

[0048] During engine start-up of the internal combustion engine, by adjusting the relative rotational angle phase position in the direction of the earlier valve control time, i.e., by rotating the rotor 2 in a clockwise direction relative to the stator 1, the first pressure medium outflow channels or through-holes 14, 15 on the bearing surface 10 are covered in a pressure medium-tight or gas-tight manner by the outer diameter of the rotor 2, while the second pressure medium outflow channels or elbow grooves 15, 16 are covered in a pressure medium-tight or gas-tight manner by the bearing surface 10 on the inner diameter of the stator 1. In order to avoid unnecessary pressure medium leakage at the pressure medium outflow connections 11, 12, the bearing surface 10 is designed for sealing with a corresponding width B in the circumferential direction or the rotational direction.

[0049] To quickly disconnect pressure medium outflow connections 11, 12 from the surrounding environment during engine startup, the elbow length S is set to adjust the rotational angle α of rotor 2 and camshaft by 1° to 2° based on the relative rotational angle phase position during engine startup. Free second ends 19, 20 of arcuate grooves 15, 16 communicate with pressure chamber 3 along the elbow length for pressure medium outflow during engine standstill. Thus, pressure medium outflow connections 11, 12 can be disconnected during engine startup by adjusting the relative rotational angle phase position toward an earlier valve control time, so that rotor 2 is rotated 1° to 2° relative to stator 1 and away from the maximum retarded position at retarded stop 7.

[0050] The engine is started from a maximum retarded position 7 which is set when the internal combustion engine is at a standstill. Therefore, when the intake gas exchange valve of the internal combustion engine is controlled by a camshaft phaser, the intake gas exchange valve can be kept open for a short time during the first engine stroke during the starting process, thereby enabling a short-term decompression of the engine during the starting process.

[0051] Furthermore, by allowing pressure medium to at least partially escape from the pressure chamber to the surroundings during engine standstill of the internal combustion engine, the relative rotational angle phase position during engine startup can be adjusted from the most retarded position to an intermediate position between the most retarded position 7 and the most advanced position 8 within a fraction of a second for further operation of the internal combustion engine. Consequently, the camshaft phaser according to the present invention can be used particularly advantageously in vehicles with hybrid drives, in which the internal combustion engine can be started very quickly by the electric motor of the hybrid drive and can be easily returned to a defined standstill position.

[0052] Due to the rapid regulation and short-term decompression of the internal combustion engine during engine starting, disturbances caused by noise and vibrations, which are known as NVH (noise, vibration and harshness) problems, can be reliably avoided.

[0053] Figure 4A second exemplary embodiment of a camshaft phaser according to the present invention is shown, wherein, in addition to the Figure 1 and Figure 2 In addition to the first embodiment, in addition to the first pair of two pressure medium outflow connections 11, 12 arranged diametrically opposite one another on the stator 1 and the rotor 2, a second pair of two pressure medium outflow connections 28, 29 arranged diametrically opposite one another on the stator 1 and the rotor 2 are provided. The second pair of pressure medium outflow connections 28, 29 serves as a direct connection to the surroundings for discharging pressure medium from the two remaining pressure chambers 3 of the camshaft phaser, which are arranged diametrically opposite one another on the stator 1 and the rotor 2, during engine standstill of the internal combustion engine. Thus, all four pressure chambers 3 of the camshaft phaser can be directly connected to the surroundings for the outflow of pressure medium due to gravity during engine standstill and can be closed again in a pressure-tight manner during engine startup.

[0054] Here, the second pair of pressure medium outflow connections 28, 29 is arranged in a rotationally offset manner by 90° relative to the first pair of pressure medium outflow connections 11, 12 and is designed similarly to the first pair of pressure medium outflow connections, so that the second pair of pressure medium outflow connections 28, 29 also functions similarly during operation. Therefore, the second pair of pressure medium outflow connections 28, 29 comprises first pressure medium outflow channels 30, 31, which are designed as diametrically opposed radial through-holes arranged in alignment on the web 9 of the stator 1 in the region of the bearing surface 10. The first pressure medium outflow channels are each arranged in the above-described manner to correspond to second pressure medium outflow channels 32, 33 on the outer diameter of the rotor 2, which are designed as recesses or elbow grooves.

[0055] In correspondence with the first pair of pressure medium outflow connections 11, 12, the elbow grooves 32, 33 communicate with the respective through-holes 30, 31 via first ends 37, 38 in the region of the bearing surface 10 of the stator 1 during engine standstill in the illustrated maximum retarded position 7 of the camshaft phaser, and communicate with the respective pressure chamber 3 via free second ends 39, 40. During engine startup, by adjusting the relative rotational angle phase position, the through-holes 30, 31 in the stator 1 can again be covered in a pressure-tight manner by the outer diameter of the rotor 2, and the elbow grooves 32, 33 in the rotor 2 can again be covered in a pressure-tight manner by the bearing surface 10 on the inner diameter of the stator 1.

[0056] In this way, when the internal combustion engine is at a standstill, pressure medium can flow directly from all four pressure chambers 3 of the camshaft phaser to the surrounding environment due to gravity. This option allows the outflow of pressure medium from the pressure chambers 3 due to gravity to be optimized in any engine standstill position.

[0057] Reference Signs List

[0058] 1 stator

[0059] 2 rotors

[0060] 3 Pressure chamber

[0061] 4 blades

[0062] 5 Opening

[0063] 6 Opening

[0064] 7 Delay stop, maximum delay position

[0065] 8 Advance stop, maximum advance position

[0066] 9 belly plate

[0067] 10 Support surface

[0068] 11 Pressure medium outflow connection

[0069] 12 Pressure medium outflow connection

[0070] 13 First pressure medium outflow channel, through hole

[0071] 14 First pressure medium outflow channel, through hole

[0072] 15 Second pressure medium outflow channel, recess, elbow groove

[0073] 16 Second pressure medium outflow channel, recess, elbow groove

[0074] 17 end

[0075] 18 end

[0076] 19 end

[0077] 20 end

[0078] 21 Ring Channel

[0079] 22 Through opening

[0080] 23 Effective direction of gravity

[0081] 24 Locking mechanism

[0082] 25 Spring

[0083] 26 Locking pin

[0084] 27 Rotation and center axis

[0085] 28 Pressure medium outflow connection

[0086] 29 Pressure medium outflow connection

[0087] 30 First pressure medium outflow channel, through hole

[0088] 31 First pressure medium outflow channel, through hole

[0089] 32 Second pressure medium outflow channel, recess, elbow groove

[0090] 33 Second pressure medium outflow channel, recess, elbow groove

[0091] 34 threaded connectors

[0092] 35 driving wheel

[0093] 36 Sealing element

[0094] 37 end

[0095] 38 end

[0096] 39 end

[0097] 40 end

[0098] X-axis height

[0099] S elbow length

[0100] α rotation angle

[0101] D diameter

[0102] B Width

[0103] T Depth

Claims

1. A hydraulic camshaft phaser for variable valve control of an internal combustion engine, the hydraulic camshaft phaser comprising a stator (1) and a rotor (2) and a plurality of pressure chambers (3), the plurality of pressure chambers being defined by the stator and the rotor and into which a pressure medium can be introduced to adjust a relative rotational angular phase position between the stator (1) and the rotor (2), characterized in that At least one pressure medium outflow connection (11, 12, 28, 29) to the surroundings is provided so that in a rotational angle phase position for enabling a maximum delayed valve control time of the internal combustion engine, pressure medium flows out of at least one pressure chamber (3) into the surroundings due to gravity during an engine standstill of the internal combustion engine, the pressure medium outflow connection being able to be closed again during engine starting by adjusting the relative rotational angle phase position.

2. The hydraulic camshaft phaser according to claim 1, characterized in that The pressure medium outflow connection (11, 12, 28, 29) comprises at least one first pressure medium outflow channel (13, 14, 30, 31) extending from the outer diameter of the stator (1) to at least one bearing surface (10) on the inner diameter, and at least one second pressure medium outflow channel (15, 16, 32, 33) located on the outer diameter of the rotor (2), wherein the second pressure medium outflow channel is connected to the pressure chamber (3) on the one hand and to the first pressure medium outflow channel (13, 14, 30, 31) on the other hand when the engine is at a standstill.

3. The hydraulic camshaft phaser according to claim 2, characterized in that During engine startup, by adjusting the relative rotational angular phase position, the first pressure medium outflow channel (13, 14, 30, 31) can be covered in a pressure-tight manner by the outer diameter of the rotor (2), and the second pressure medium outflow channel (15, 16, 32, 33) can be covered in a pressure-tight manner by the bearing surface (10) on the inner diameter of the stator (1).

4. The hydraulic camshaft phaser according to claim 2, wherein: The first pressure medium outflow channel (13, 14, 30, 31) is designed as a radial through hole on the stator (1), and the second pressure medium outflow channel (15, 16, 32, 33) on the outer diameter of the rotor (2) is designed as a radial elbow groove extending in the circumferential direction.

5. The hydraulic camshaft phaser according to claim 4, characterized in that During engine standstill, the elbow grooves (15, 16, 32, 33) on the outer diameter of the rotor (2) communicate with the through holes (13, 14, 30, 31) in the circumferential direction via first ends (17, 18) in the region of the support surface (10) of the stator (1), and communicate with the pressure chamber (3) via free second ends (19, 20) extending outside the region of the support surface (10).

6. The hydraulic camshaft phaser according to claim 5, characterized in that During engine standstill, the elbow groove (15, 16, 32, 33) extends by a predetermined elbow length (S) in a direction for adjusting the relative rotational angle phase position relative to engine start-up through the free second end portion (19, 20) outside the area of ​​the support surface (10), wherein the elbow length (S) corresponds to an adjustment of the relative rotational angle phase position by a rotation angle (α) of 1° to 2° during engine start-up.

7. The hydraulic camshaft phaser according to claim 1, characterized in that At least two pressure medium outflow connections (11, 12) to the surrounding environment, which are arranged diametrically opposite to each other on the stator (1) and the rotor (2), are arranged so that pressure medium flows out to the surrounding environment from at least two pressure chambers (3) arranged diametrically opposite to each other on the stator (1) and the rotor (2) due to the action of gravity during engine standstill of the internal combustion engine.

8. The hydraulic camshaft phaser according to claim 2, characterized in that Two first pressure medium outflow channels (13, 14) arranged diametrically opposite to each other on the stator (1) in the region of the support surface (10) and designed as radial through holes, and two second pressure medium outflow channels (15, 16) arranged diametrically opposite to each other on the rotor (2) and designed as radial elbow grooves extending on the outer diameter in the circumferential direction are arranged so that pressure medium flows out from two pressure chambers (3) arranged diametrically opposite to each other on the stator (1) and the rotor (2) into the surrounding environment due to the action of gravity during engine standstill of the internal combustion engine.

9. The hydraulic camshaft phaser according to claim 2, characterized in that At least two pairs of two first pressure medium outflow channels (13, 14, 30, 31) arranged diametrically opposite to each other in the region of the support surface (10) on the stator (1) and designed as radial through holes, and at least two pairs of two second pressure medium outflow channels (15, 16, 32, 33) arranged diametrically opposite to each other on the rotor (2) and designed as radial elbow grooves extending on the outer diameter in the circumferential direction are arranged so that pressure medium flows out from the two pairs of two pressure chambers (3) arranged diametrically opposite to each other on the stator (1) and the rotor (2) into the surrounding environment due to the action of gravity during engine standstill of the internal combustion engine.

10. A method for operating a hydraulic camshaft phaser according to one of the preceding claims, characterized in that The camshaft phaser is adjusted from an adjustment position for enabling a maximum retarded valve control time of the internal combustion engine during an engine standstill of the internal combustion engine to an intermediate adjustment position between the maximum retarded adjustment position and the maximum advanced adjustment position in less than one second during engine starting to operate the internal combustion engine by generating an alternating torque on a camshaft of the internal combustion engine during operation.

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