CN112832883A

CN112832883A - Electrical camshaft adjuster and method for producing a camshaft adjuster

Info

Publication number: CN112832883A
Application number: CN202011318732.7A
Authority: CN
Inventors: 于尔根·韦伯; 雷纳·奥特尔巴赫
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Holding China Co Ltd
Priority date: 2019-11-25
Filing date: 2020-11-23
Publication date: 2021-05-25
Anticipated expiration: 2040-11-23
Also published as: DE102019131779A1; CN112832883B

Abstract

The invention relates to an electric camshaft adjuster (1) for a drive train of a motor vehicle and to a method for producing a camshaft adjuster (1). The camshaft adjuster comprises a drive wheel (2) which can be driven by an endless traction mechanism and a driven hollow wheel (3) which is arranged coaxially with the drive wheel (2) and can be rotated relative to the drive wheel (2) by means of an electric motor, wherein the driven hollow wheel (3) has an extension (4) which extends axially thereof and has a bearing point (5) for radial support at a housing (6) and is intended for fastening at a camshaft (7), wherein the extension (4) has a bearing (20) on its outer surface for bearing the camshaft (7).

Description

Electrical camshaft adjuster and method for producing a camshaft adjuster

Technical Field

The invention relates to an electric camshaft adjuster for a drive train of a motor vehicle. Camshaft adjusters are used to adjust the phase of a camshaft relative to a crankshaft. The camshaft adjuster has a drive wheel which can be driven by the endless traction mechanism and a driven hollow wheel which is arranged coaxially with the drive wheel and can be rotated relative to the drive wheel by means of an electric motor. The driven hollow wheel has an axially extended extension, which has a bearing point for radial support at the housing and is intended for fastening to the camshaft.

Background

Electrical camshaft adjusters usually have: the drive device comprises a stator housing/drive wheel which can be coupled in rotation with the crankshaft, a driven ring gear which can be coupled in rotation with the camshaft and can be rotated relative to the drive wheel, and an electrical actuating device for controlling the rotation of the driven ring gear relative to the drive wheel/stator housing. The adjusting device has an adjusting gear, which is coupled to the camshaft. The adjusting device can have, for example, an electric motor, an adjusting gear coupled to the driven ring gear, and a clutch coupling the electric motor to the adjusting gear.

Such an electric camshaft adjuster is known, for example, from DE 102004062037 a 1. Disclosed therein is a camshaft adjuster for adjusting the relative angular position of a camshaft with respect to a crankshaft of an internal combustion engine, having an electrical adjusting device and an adjusting gear mechanism which is in driving connection with a drive wheel driven by the crankshaft, wherein the adjusting gear mechanism is connected to an engine lubrication circuit and has a housing which is sealed with respect to the environment via a sealing element.

The problem with camshaft adjusters is that additional connecting elements, such as centering screws, laser structures at joints in screw connections, camshaft end pieces which have to be connected to the camshaft, and screwing processes at the customer site are required, so that the connection between the electric camshaft adjuster and the camshaft is expensive to produce. Furthermore, the previous connection between the camshaft and the camshaft adjuster causes stresses in the driven ring gear and requires additional installation space in the transmission, for example for the bolt head of a centering bolt radially inside the inner ring of the adjusting shaft of the transmission.

Disclosure of Invention

It is therefore an object of the present invention to avoid or at least reduce the disadvantages of the prior art. In particular, an electrical camshaft adjuster and a method for producing/mounting a camshaft adjuster are provided, wherein the above-described system components do not have to be transported through the camshaft and the connection of the camshaft to the camshaft adjuster is improved.

According to the invention, this object is achieved in a device of this type in that the extension has a bearing for mounting the camshaft on its outer surface. That is, the camshaft, in particular the pipe section of the camshaft, can be mounted directly, i.e. without additional camshaft end pieces and/or centering bolts, on the bearing for the extension. In other words, the driven ring gear is designed according to the invention in such a way that the camshaft (instead of the axial screw mounting) can be mounted on the drive ring gear via a direct force-fit connection, form-fit connection, frictional connection or material connection, for example by gluing or welding. A particularly cost-effective and secure connection between the drive ring gear and the camshaft can thus be provided. The ring gear is preferably designed such that the camshaft can be mounted without fastening elements, i.e. without separate fastening elements, such as bolts or the like.

This has the advantage that connecting elements for producing a connection between the electric camshaft adjuster and the camshaft, such as centering screws, laser structures at joints in the screw connection, camshaft end pieces which have to be connected to the camshaft, and also a screwing operation at the customer site during the final assembly, can be dispensed with. Since the camshaft can be mounted or fastened directly on the outer surface of the extension, i.e. via the bearing, on the camshaft adjuster, in particular the driven hollow wheel, an additional fastening element is dispensed with. This in turn has the advantage that, by eliminating the fastening elements, no stresses and/or deformations are introduced into the driven ring gear and additional installation space can be obtained in the transmission.

According to a preferred embodiment, the outer surface of the extension can be designed to bear against a radially inner surface of the camshaft. That is, the extension is built into the camshaft or the camshaft is journaled on the extension. In particular in the case of a camshaft with a camshaft tube/tube section, the rigidity of the tube section can therefore be additionally improved.

According to an alternative preferred embodiment, the inner surface of the extension can be designed for bearing against the radially outer surface of the camshaft. That is, the extension is sleeved onto the camshaft or the camshaft is inserted into the extension.

In an advantageous development, the extension can have a knurling in the region of the abutment. This has the advantage that, on the one hand, the surface of the extension in the region of the bearing is increased and, on the other hand, a knurled connection between the camshaft and the extension can be established. Such a knurled connection has a significantly higher strength, in particular a strength against rotation, than a smooth connection. Preferably, the knurling can extend over the entire circumference of the extension. This achieves a circumferentially uniform and particularly high strength.

It is particularly preferred to provide the region with the centering surface axially spaced from the knurling at the extension in order to center the driven hollow wheel relative to the camshaft during the mounting process. Preferably, the centering surface is arranged on an axial side of the knurling facing the camshaft.

It is also preferred that the camshaft is fixed to the bearing, wherein the knurling is pressed into the camshaft in the region of the bearing with a press fit. That is, the driven ring gear is preferably connected to the camshaft by a knurled press fit. This results in a non-releasable, i.e. non-releasable elastic-plastic connection between the camshaft and the driven hollow shaft without damage.

It is also advantageous if the camshaft adjuster has a machine element which surrounds and closes on the circumference of the camshaft, i.e. is uninterrupted/surrounds in the circumferential direction, and which forms a press fit with the camshaft in the region radially outside the bearing. The machine element can be formed, for example, by a sensor wheel/trigger disk or a cam of a camshaft. Since the machine element is arranged directly radially outside the bearing, i.e. at the same axial height, a force acting counter to the press fit between the camshaft and the driven hollow wheel can be exerted. Thereby reducing distortion and/or stress in the camshaft tube. In addition, the press-fit connection between the camshaft and the driven hollow wheel can be additionally increased thereby.

The press fit between the camshaft and the machine element is expediently matched to the press fit between the driven hollow wheel and the camshaft in such a way that the stresses produced by the press fit and the press fit are substantially balanced. Stresses in the camshaft can thereby be avoided.

It is also preferred that the extension has a higher material strength than the camshaft. This makes it easier to press the extension into the softer material of the camshaft.

It is also advantageous if the extension has a contour which, when the camshaft is mounted on a bearing for the camshaft formed by the extension, forces a non-releasable, preferably elastic-plastic, connection of the camshaft to the driven hollow wheel. Knurling, for example, forms such a profile.

The object of the invention is also achieved by a method for producing a camshaft adjuster according to the invention, wherein the radial shaft sealing ring, the rolling bearing and the sensor wheel are pre-mounted on the axial extension of the driven hollow wheel before a knurled press fit between the extension and the tube section of the camshaft is established. This eliminates the need to transport the radial shaft sealing ring, the rolling bearing and/or the sensor wheel through the camshaft.

According to a further aspect of the invention, the extension of the driven ring gear has at least one, for example at least partially radially oriented, oil drain channel for draining off lubricating oil in addition to at least one, for example at least partially radially oriented, oil inlet channel for feeding in lubricating oil. In other words, at least one oil drain channel is formed in the extension of the driven ring gear, through which oil can be drained away from the interior of the driven ring gear. In other words, the oil can be conducted (lubricated) in particular outside the driven ring gear, preferably outside the entire oil seal system of the camshaft adjuster, particularly preferably inside the engine housing in which the camshaft adjuster is mounted, by means of the oil drain channel. Preferably, the at least one oil inlet channel and/or the at least one oil outlet channel are oriented precisely in the radial direction, since this allows particularly simple introduction. The lubricating oil is guided, in particular via a so-called P channel, via at least one oil inlet channel into a radially inner cavity of the driven hollow wheel. From the hollow space, the lubricating oil is conducted, for example, to a clutch of the adjusting gear and/or the camshaft adjuster, to a radial bearing region between the driven ring gear and the drive wheel and/or to a radial bearing region between the driven ring gear and a sealing cap of the camshaft adjuster, and/or to the electric motor. The back pressure of the lubricating oil introduced into the externally sealed electric camshaft adjuster is reduced by the provision of the at least one oil drain channel according to the invention. This has the advantage that by guiding the lubricating oil through the oil drain channel to the outside, i.e. from the sealing region of the camshaft adjuster to the outside, build-up of an oil back pressure can be prevented or an oil back pressure can be reduced or eliminated by providing at least one oil drain channel. Damage to the seal for sealing the wet chamber of the camshaft adjuster is thereby avoided.

According to a preferred embodiment, the at least one oil discharge passage may be arranged closer to the camshaft-side end of the extension than the at least one oil intake passage. The discharged oil can thus be guided more easily toward the space outside the camshaft or the housing. Preferably, therefore, the at least one oil drainage channel is arranged on the camshaft-side axial side of the bearing point.

Alternatively, the at least one oil intake passage may also be arranged closer to the camshaft-side end of the extension than the at least one oil discharge passage. That is, the at least one oil drain passage is disposed closer to the support site of the extension portion than the at least one oil intake passage. Preferably, the oil drain channel can be arranged axially (directly) adjacent to the bearing location for the camshaft. The drained oil can then be conducted away from the bearing arrangement through the engine housing via the bearing. However, this has the disadvantage that contaminants of the camshaft adjuster are carried by the discharged oil into the bearings, for example rolling bearings, arranged at the bearing points.

The extension of the driven ring gear has an end section which is designed in such a way that it is arranged outside the housing in the mounted state of the camshaft adjuster. According to a preferred embodiment, at least one oil drain channel, in particular at least one opening to the radial outside of the extension, can be arranged in this end section. This has the advantage that the discharged oil is guided directly in the region outside the engine housing, so that, for example, the circulating traction mechanism connected to the drive wheels is not in contact with the oil.

According to an advantageous embodiment, at least one oil inlet channel and/or at least one oil drain channel fluidly connects the radially outer side of the extension with the radially inner side of the extension. That is, oil can be introduced from the outside, for example via a P channel in the housing, into the cavity of the driven hollow wheel. From the cavity, oil can be supplied to the component to be lubricated and/or to the connecting point of the camshaft adjuster. The oil can also be drained/drained from the cavity through the oil drain channel. This has the advantage that an oil drain formed by an oil drain channel is provided in relation to an externally sealed system, which is formed in particular by the cavity and the component to be lubricated arranged within the camshaft adjuster, so that the back pressure is significantly reduced. In other words, the channel for feeding the lubricating oil into the camshaft adjuster and for discharging the lubricating oil from the camshaft adjuster runs directly in the driven ring gear. The channels can thus be integrated almost unchanged in terms of installation space.

It is also advantageous if the extension has a plurality of oil inlet channels and/or a plurality of oil discharge channels. In this way, oil can be introduced into the cavity or removed from the cavity in a suitable manner. It is also preferred that the plurality of oil inlet passages extend in a common first plane. The first plane may in particular be a radial plane perpendicular to the axis of the camshaft adjuster. Alternatively or additionally, it is preferred that the plurality of oil drainage channels run in a common second plane. The second plane may in particular be a radial plane perpendicular to the axis of the camshaft adjuster. This has the advantage that the oil is introduced axially at the same location, but circumferentially via a plurality of oil inlet channels or is removed via a plurality of oil outlet channels, so that the oil can be conducted further from there better and more controlled. It is also preferred that the first plane is parallel to and axially spaced from the second plane.

It is also expedient if a plurality of oil inlet channels are oriented identically and/or a plurality of oil outlet channels are oriented identically. That is, the oil intake passage or the oil discharge passage may also be arranged in parallel with each other on the axis.

According to a preferred embodiment, the at least one oil discharge channel can be configured relative to the at least one oil inlet channel in such a way that the at least one oil discharge channel performs a throttling effect. The oil flow can thus be appropriately guided into and out of the driven ring gear.

According to a preferred embodiment, the at least one oil discharge channel can have a smaller diameter or at least a smaller cross section than the at least one oil inlet channel. This enables a throttling effect to be achieved in a simple manner. Alternatively, the number of oil inlet passages can be greater than the number of oil discharge passages. In other words, it is important that the total flow into the driven ring gear via the oil inlet channel is greater than the total flow out of the driven ring gear via the oil outlet channel.

In the particular illustrated development, the drive wheel is in operative contact with a dry-running belt. That is, the electric camshaft adjuster is incorporated into a dry belt system. In particular in the case of dry belt systems, it is important that the seals used are not damaged, since otherwise the belt would be wetted by oil. The drive wheel can also be brought into operative contact with a wet-running chain. That is, the electric camshaft adjuster is built into the chain system.

In particular, it is preferred that the wet space formed within the camshaft adjuster can be sealed off from the housing via a first radial shaft sealing ring, which is mounted on a first sealing cap connected in a rotationally fixed manner to the drive wheel, and/or via a second radial shaft sealing ring, which is mounted on a second sealing cap connected in a rotationally fixed manner to the drive wheel, the oil being able to be introduced into the wet space via the oil inlet channel and being able to be discharged from the wet space via the oil outlet channel. Preferably, the first sealing cap is arranged on the axial side of the drive wheel facing away from the camshaft. Preferably, the second sealing cap is arranged on the axial side of the drive wheel facing the camshaft. In other words, a fluid connection is produced between the at least one oil inlet channel and a radial shaft seal ring which is slipped onto the first seal cap connected to the drive wheel. In other words, a second sealing cap is provided on the opposite side of the drive wheel, between which a further radial shaft sealing ring is sealingly inserted.

In other words, the invention relates to an electric camshaft adjuster having an improved camshaft coupling and an improved lubricant supply.

On the one hand, the problem of the time-consuming assembly of the camshaft adjuster, which is caused by the individual system elements, such as the radial shaft sealing rings, the rolling bearings and/or the sensor wheel, having to travel through the entire camshaft in order to be transported to the assembly site, is solved by the camshaft adjuster according to the invention. According to the invention, a non-releasable knurled press fit is formed between the electric camshaft adjuster and the camshaft or camshaft body. The press fit forms an elastic-plastic connection and is therefore not releasable without damage. Alternatively or additionally, an adhesive and/or welded connection can be provided between the electric camshaft adjuster and the camshaft. The pre-assembly of the radial shaft sealing ring, the rolling bearing and the sensor wheel at the axial extension of the driven hollow wheel is carried out before the knurled press fit is established. This makes it possible to dispense with the further installation of system components during the installation of the engine. The extension of the driven ring gear has a knurled section at its end (on the right in the drawing), by means of which the driven ring gear is pressed axially in a pressed-on manner into the tubular section of the camshaft of the design. In addition, the knurling can be hardened, so that the knurled toothing engages in an elastic-plastic manner in the softer camshaft tube and establishes a gapless form-fit with the tube section of the camshaft. This has the advantage that connecting elements, such as centering bolts, laser structures or camshaft end pieces, and the screwing process at the customer site can be eliminated. The press-fit connection can be reinforced by a trigger disk/sensor wheel which is fitted onto the tube section of the camshaft in the axial region of the press-fit connection. Furthermore, stresses and deformations in the driven ring gear can be reduced by the elimination of the screw connection. The rigidity of the inner ring of the rolling bearing in the transmission can also be increased by eliminating the bolt head of the centering bolt, so that the inner diameter of the inner ring in the additional installation space is reduced.

On the other hand, the problem that can be solved by the camshaft adjuster according to the invention is that a back pressure is generated in the wet chamber/wet region of the camshaft adjuster, which is sealed off from the outside, as a result of the introduction of lubricating oil from the P channel at the camshaft adjuster, which leads to leakage or wear of the sealing lips of the radial shaft sealing rings. According to the invention, a discharge opening is provided at the end of the axial extension of the driven ring gear. It is thus possible to prevent back pressure from building up by feeding lubricating oil into the oil-sealed mechanical transmission, since excess lubricating oil is led back into the engine interior on the axial right outside the camshaft adjuster via a plurality of outlet openings at the end of the axial extension of the driven ring gear. This also has the advantage that the oil inlet channel and the oil outlet channel run directly in the driven ring gear.

Drawings

The invention is elucidated below with the aid of the drawing. In which is shown:

figure 1 shows a longitudinal section through a camshaft adjuster according to the invention in a camshaft adjustment system,

figure 2 shows a longitudinal section through a camshaft adjuster,

figure 3 shows a longitudinal section through a driven hollow wheel of a camshaft adjuster,

figure 4 shows a perspective view of the driven ring gear,

fig. 5 shows a perspective view of the driven ring gear rotated relative to the view of fig. 4, an

Fig. 6 shows a perspective view of a part of a camshaft adjustment system.

The drawings are exemplary only and are for the purpose of illustrating the invention. Like elements are provided with like reference numerals. The features of the various embodiments may be interchanged with one another.

Detailed Description

Fig. 1 and 2 show an electrical camshaft adjuster 1 according to the invention for a drive train of a motor vehicle. The camshaft adjuster 1 has a drive wheel 2. The drive wheel 2 can be driven by a circulating traction mechanism. The drive wheel 2 is connected to a crankshaft, not shown. The camshaft adjuster 1 has a driven hollow wheel 3 arranged coaxially with the drive wheel 2. The driven ring gear 3 can be rotated relative to the drive wheel 2 by means of an electric motor. The driven ring gear 3 has an extension 4 extending axially thereof. A bearing point 5 for radial support at a housing 6 is formed at the extension 4. The extension 4 is ready for fixing at the camshaft 7. Preferably, the extension 4 has a higher material strength than the camshaft 7.

According to the invention, the extension 4 has at least one at least partially radially oriented oil inlet channel 8 and at least one at least partially radially oriented oil discharge channel 9. The oil inlet channel 8 is particularly precisely oriented in the radial direction. The oil drain channel 9 is particularly precisely oriented in the radial direction. Via the oil inlet channel 8, oil, such as lubricating oil, can be fed in. Via the oil discharge channel 9, oil can be discharged. A wet chamber 10 is formed in the camshaft adjuster 1, in which the lubricating oil introduced via the oil inlet channel 8 is located. The wet chamber 10 is sealed from the outside. The oil is removed from the wet space 10 via the oil drain channel 9 according to the invention, so that the back pressure is reduced.

The oil inlet channel 8 connects the radial outer side of the driven ring gear 3 to the radial inner side of the driven ring gear 3. The oil drain channel 9 has an inlet end which is open toward a radially outer region of the driven ring gear 3 and an outlet end which is open toward the cavity 11 of the driven ring gear 3. The oil inlet channel 8 thus opens into the cavity 11 of the driven hollow wheel 3. The cavity 11 is part of the wet chamber 10. The oil drain channel 9 connects the radially inner side of the driven ring gear 3 to the radially outer side of the driven ring gear 3. The oil drain channel 9 thus has an inlet end which is open toward the cavity 11 and an outlet end which is open toward a radially outer region of the driven hollow wheel 3.

The above-mentioned at least one oil discharge passage 9 is arranged closer to the camshaft-side end portion of the extension portion 4 than the above-mentioned at least one oil intake passage 8. Alternatively, the above-mentioned at least one oil intake passage 8 may be arranged closer to the camshaft-side end of the extension portion 4 than the above-mentioned at least one oil discharge passage 9, which is not shown in the drawings. The oil drain channel 9 is arranged on the camshaft-side axial side of the bearing point 5. The oil drain channel 9 can also be arranged in the axial region of the bearing point 5, which is not shown in the drawing. The oil inlet passage 8 is arranged on the camshaft-side axial side of the bearing point 5.

The extension 4 has an end section 12 which is configured in such a way that it is arranged outside the housing 6 in the mounted state of the camshaft adjuster 1, wherein at least one oil drain channel 9 is arranged in the end region 12. The camshaft adjuster 1 is mounted in a housing 6, wherein a wet chamber 10 is sealed off from a dry chamber 13 in the housing 6. The end section 12 of the driven ring gear 3 (in the installed state) protrudes from the housing 6. The oil drain channel 9 or at least the outlet end of the oil drain channel 9 is arranged in the end section 12, so that the lubricating oil can be conducted out of the housing 6 through the oil drain channel 9. As a result, the lubricating oil is not discharged from the driven ring gear 3 at a point within the housing 6, i.e., in the wet chamber 13. Alternatively, the oil drain channel 9 can be arranged in such a way that the lubricating oil can be conducted away from the dry chamber 13 or from the camshaft adjuster 1 via a channel in the housing 6.

In the embodiment shown, the driven hollow wheel 3 has a plurality of oil inlet channels 8. In the embodiment shown, the driven ring gear 3 has a plurality of oil drainage channels 9. The oil inlet channel 8 is oriented radially. The oil inlet channels 8 are arranged in a common first plane. The first plane is a radial plane perpendicular to the axis of rotation of the camshaft adjuster 1. The oil inlet channels 8 are evenly distributed over the circumference of the extension. The oil inlet passages 8 have the same cross section, respectively. The oil inlet channel 8 opens into the cavity 11 from an annular channel 14 formed in the housing 6. The oil is introduced into the annular passage 14 via a P passage, not shown, arranged in the housing 6. The oil discharge channel 9 is oriented radially. The oil discharge channels 9 are arranged in a common second plane. The second plane is a radial plane perpendicular to the axis of rotation of the camshaft adjuster 1. The first and second planes are parallel to each other and axially offset. The oil discharge channels 9 are arranged evenly distributed over the circumference of the extension. The oil discharge channels 9 each have the same cross section.

The at least one oil discharge channel 9 is designed relative to the at least one oil inlet channel 8 in such a way that the at least one oil discharge channel performs a throttling effect. In the embodiment shown, the oil discharge channel 9 has a smaller diameter than the oil intake channel 8.

The drive wheel 2 is in operative contact with a dry running belt 15. Torque is introduced into the camshaft adjuster 1 via the belt 15. A belt 15 is arranged in the drying chamber 13. Alternatively, the drive wheel 2 can be driven via a chain, for example, running wet, which is not shown.

The wet chamber 10 formed inside the camshaft adjuster 1 is sealed off from the dry chamber 13. For this purpose, a seal is provided between the camshaft adjuster 1 and the housing 6. The wet chamber 10 is sealed off from the housing 6, i.e. from the dry chamber 13 formed in the housing 6, via a first radial shaft sealing ring 16. A first radial shaft seal ring 16 is fitted (radially outside) on a first seal housing 17. The first sealing cap 17 is connected in a rotationally fixed manner to the drive wheel 2. The first sealing cap 17 is arranged on the axial side of the drive wheel 2 facing away from the camshaft. The wet chamber 10 is sealed off from the housing 6, i.e. from the dry chamber 13 formed in the housing 6, via a second radial shaft sealing ring 18. A second radial shaft seal ring 18 is fitted (radially outside) over a second seal housing 19. The second sealing cap 19 is connected in a rotationally fixed manner to the drive wheel 2. The second sealing cap 19 is arranged on the axial side of the drive wheel 2 facing the camshaft.

According to the invention, the extension 4 has a bearing 20 on its outer surface for supporting the camshaft 7. That is, the tube section 21 of the camshaft 7 bears directly against the bearing 20. The outer surface of the extension 4 is therefore designed to rest against the radially inner surface 22 of the camshaft 7 or of the tube section 21. In other words, the extension 4 of the driven hollow wheel 3 is connected directly, i.e. without an intermediate piece, for example a camshaft end piece, to the tube section 21. The cams of the camshaft 7 are mounted directly on the circumference of the tube section 21.

Fig. 3 to 5 show different views of the driven ring gear 3. The abutment 20 is configured at the end section 12 of the extension 4. The support 20 is formed at the flange 22. The flange 22 forms an axial end of the extension 4. The extension 4 has a smaller outer diameter in the region of the flange 22 than in a region axially spaced apart therefrom, for example in the region of the bearing point 5. In the embodiment of the extension 4 shown, the intermediate region 24 axially adjoins the bearing region 23 in which the bearing point 5 is arranged. The flange 22 axially abuts the intermediate region 24. The cavity 11 does not extend axially as far as the flange 22.

The extension 4 has a knurling 25 in the region of the support 20. Knurling 25 is formed on the outer surface of the holder 20. The knurls 25 extend over the entire circumference of the extension 4. The knurl 25 has a first knurl section 26 and a second knurl section 27. The first knurled section 26 serves as a centering surface for centering the driven hollow wheel 3 relative to the camshaft 7. Thus, the first knurled section 26 serves for centering when being pressed into the tube section 21/during the mounting process. The first knurled section 26 is arranged closer to the axial end of the extension 4 facing the camshaft than the second knurled section 27. The first knurled section 26 has a smaller outer diameter than the second knurled section 27. The second knurled section 27 creates a press fit with the camshaft 7. The second knurled section 27 thus serves for a knurled press fit.

The extension 4 has a contour which, when the camshaft 7 is mounted on a bearing 20 for the camshaft 7 formed by the extension, forces a non-releasable, preferably elastic-plastic, connection of the camshaft 7 to the driven hollow wheel 3. This elastic-plastic connection is produced by pressing the knurling 25 into the tube section 21 of the camshaft 7.

The flange 22 merges into the intermediate section 24 via a step 28. The outer diameter of the extension 4 increases from the outer diameter of the flange 22 via an axial step 28. In the mounting phase, the camshaft 7 rests against an axial end face of the step 28. The step 28 thus serves as an axial bearing for the camshaft 7. In order to better produce the knurls 25, relief grooves are formed in the region of the step 28.

The camshaft adjuster 1 has a machine element 29 which surrounds and closes on the circumference of the camshaft 7. Closed means that the machine element 29 is configured continuously/circumferentially in the circumferential direction. In the embodiment shown, the machine element 29 is formed by a sensor wheel 30/trigger wheel/trigger disk. The machine element 29 may also be formed by a cam, which is not shown. The sensor wheel 30 is fixed directly on the circumference of the pipe section 21. The machine element 29 is fixed to the camshaft 7 via a press fit. The machine element 29 is arranged axially in the region of the support 20. That is, the machine element 29 is mounted on the camshaft 7 in a region immediately axially outside the carrier 20.

The press fit between the camshaft 7 and the machine element 29 is coordinated with the press fit between the driven hollow wheel 3, in particular the carrier 20, and the camshaft 7 in such a way that the stresses produced by the press fit and the press fit are substantially identical. I.e. the stresses are substantially the same magnitude. The stresses act in substantially opposite directions.

The method according to the invention for producing an electrical camshaft adjuster 1 is described below with reference to fig. 2. The pre-assembly is carried out before the connection of the camshaft 7 to the camshaft adjuster 1 is established. In the pre-assembly, the radial shaft sealing ring, in this case the second radial shaft sealing ring, is pushed onto the driven hollow wheel 3, in this case the extension 4. In the pre-assembly, the bearing, in this case the rolling bearing 31, which is attached to the bearing point 5, is pushed onto the driven ring gear 3. During the preassembly, the sensor wheel 20 can also be pushed onto the driven ring gear 3. After the preassembly, a knurled press fit between the extension 4 and the tube section 21 of the camshaft 7 is produced in order to establish the connection of the camshaft 7 to the camshaft adjuster 1. For this purpose, the support 20 is pressed into the tube section by means of a knurling 25. Thereby establishing an elasto-plastic connection between the extension 4 and the camshaft 7.

List of reference numerals

1 camshaft adjuster

2 driving wheel

3 driven hollow wheel

4 extension part

5 support part

6 casing

7 camshaft

8 oil inlet channel

9 oil discharge channel

10 wet chamber

11 cavity

12 end section

13 Dry chamber

14 annular channel

15 leather belt

16 first radial shaft seal ring

17 first sealed cover

18 second radial shaft seal ring

19 second sealing cover

20 support

21 pipe section

22 flange

23 bearing area

24 middle area

25 knurling

26 first knurled section

27 second knurled section

28 step part

29 machine element

30 sensing wheel

31 rolling bearing

Claims

1. Electric camshaft adjuster (1) for a drive train of a motor vehicle, having a drive wheel (2) which can be driven by a cyclical traction mechanism and a driven hollow wheel (3) which is arranged coaxially with respect to the drive wheel (2) and can be rotated relative to the drive wheel (2) by means of an electric motor, wherein the driven hollow wheel (3) has an extension (4) which extends axially thereof and has a bearing point (5) for radial support at a housing (6) and is intended for fastening at a camshaft (7), characterized in that the extension (4) has a bearing (20) on its outer surface for bearing the camshaft (7).

2. Camshaft adjuster (1) according to claim 1, characterized in that the outer surface of the extension (4) is designed to bear against a radially inner surface of the camshaft (7).

3. Camshaft adjuster (1) according to claim 1, characterized in that the inner surface of the extension (4) is designed to bear against a radially outer surface of the camshaft (7).

4. Camshaft adjuster (1) according to one of claims 1 to 3, characterized in that the extension (4) has a knurling (25) in the region of the bearing (20).

5. Camshaft adjuster (1) according to claim 4, characterized in that a region with centering faces (25, 27) is provided axially spaced apart from the knurling (25, 26) at the extension (4) for centering the driven hollow wheel (3) relative to the camshaft (7).

6. Camshaft adjuster (1) according to claim 4 or 5, characterized in that a camshaft (7) is fixed at the bearing (20), wherein the knurling (25, 26) is pressed into the camshaft (7) in the region of the bearing (20) with a press-fit.

7. Camshaft adjuster (1) according to claim 6, characterized in that the camshaft adjuster (2) has a machine element (29, 30) which surrounds and closes on the circumference of the camshaft (7) and which forms a press fit with the camshaft (7) in the region of the radially outer region of the bearing (20).

8. Camshaft adjuster (1) according to claim 6 or 7, characterized in that the extension (4) has a higher material strength than the camshaft (7).

9. Camshaft adjuster (1) according to one of claims 6 to 8, characterized in that the extension (4) has a profile which forces a non-releasable connection of the camshaft (7) to the driven hollow wheel (3) when the camshaft (7) is slipped onto a bearing (20) for the camshaft (7) formed by the extension (4).

10. Method for producing a camshaft adjuster (1) according to one of claims 1 to 9, wherein a radial shaft sealing ring (18), a rolling bearing (31) and a sensor wheel (30) are pre-mounted on the axial extension (4) of the driven hollow wheel (3) before a knurled press fit between the extension (4) and the tube section (21) of the camshaft (7) is established.