EP3334910B1 - Adjustable camshaft with camshaft phaser - Google Patents

Description

The present invention relates to an adjustable camshaft for the valve train of an internal combustion engine, comprising an outer shaft and an inner shaft rotatable in the outer shaft, and with a phase adjuster with which the outer shaft and / or the inner shaft can be adjusted in a phase position formed about an axis of rotation, and wherein the Camshaft has a bearing section for mounting the camshaft, via which the phase adjuster can be fed with a pressure medium.

STATE OF THE ART

Adjustable camshafts are used for the variable valve train of an internal combustion engine, and the phase adjuster can be used to adjust the phase position of the inner shaft relative to the phase position of the outer shaft during the rotation of the adjustable camshaft. There is also the possibility of jointly adjusting the phase position of the inner shaft and the outer shaft relative to the phase position of a drive wheel, by means of which the camshaft is driven to rotate about the axis of rotation. So-called dual phase adjusters enable, for example, the phase position of the outer shaft and the inner shaft to be changed together, and at the same time the phase position of the inner shaft can be adjusted relative to the outer shaft.

Phase adjusters are generally operated by a pressure medium, in particular an oil, in that pressure chambers formed between a rotor and a stator of the phase adjuster are acted upon alternately by fluid. In order to enable the pressure medium to be fed to the phase adjuster rotating with the camshaft, the pressure medium is usually supplied via a bearing section on the outer shaft of the camshaft, via which the camshaft is mounted in a bearing bridge. The bearing section generally forms the outermost bearing section at the end of the camshaft, so that the outer shaft and in particular the inner shaft along with the bearing section in its longitudinal direction complete the axis of rotation and the phase adjuster adjoins the end in the direction of the axis of rotation. The rotor is usually attached to the end of the inner shaft and the stator of the phase adjuster is usually attached to the end of the outer shaft. In particular in the case of dual phase adjusters, the problem arises that, for example, four or more channels are necessary in order to pressurize the individual chambers between the rotor and stator of the phase adjuster. If the phase adjuster, in particular the rotor, is fastened to the inner shaft with a central screw, there are particular difficulties in accommodating the channels in the inner shaft and / or the outer shaft due to the reduced installation space.

For example, the DE 10 2006 028 611 A1 an adjustable camshaft with a phase adjuster, which is screwed at the end to the inner shaft with a central screw. The outer shaft is rotatably received in a bearing ring, the bearing ring being designed to rotate with the outer shaft. The bearing ring is received in a re-bearing, which is formed by the bearing bridge, for example of the camshaft module or the like, and does not rotate with it. Only two oil channels are shown which are guided to the adjusting elements of the phase adjuster and which must run over the end bearing section of the camshaft. Further oil channels are guided over a bearing section and run centrally through the inner shaft and through a gap between the inner shaft and the outer shaft. However, it is desirable to limit the fluid supply to the phase adjuster to the end bearing section, which is located near the phase adjuster on the camshaft.

Another adjustable camshaft is from the DE 10 2006 013 829 A1 known, and the inner shaft of the camshaft has a threaded bore into which a central screw can be screwed in order to fasten the phase adjuster to the camshaft. The oil channels must therefore be accommodated in the radial area between the threaded bore and the mounting flange, which is seated on the end of the outer shaft. Due to the limited space available for accommodating the oil channels, the arrangement of a dual phase adjuster, for example, is not readily possible.

A generic camshaft is also from the EP 2 527 607 A2 known. Other camshafts are for example from the WO 2013/037515 A1 and WO 2012/171672 A1 known. According to the prior art, a screw flange and a central screw connection are used to attach the phase adjuster to the camshaft end. The fastening of a screw flange via a central screw connection can be complex with regard to assembly.

DISCLOSURE OF THE INVENTION

The object of the invention is the development of an adjustable camshaft with an improved arrangement of a phase adjuster at the end of the camshaft. In particular, it is the object of the invention to reduce the assembly effort of the camshaft.

This object is achieved on the basis of an adjustable camshaft according to the preamble of claim 1 in conjunction with the characterizing features. Advantageous developments of the invention are specified in the dependent claims.

According to the invention, the connection of the rotor to the screw flange has screw elements, the screw elements being arranged at a distance from the axis of rotation. In principle, a single screwing element can be sufficient to connect the rotor of the phase adjuster to the screwing flange, but advantageously several screwing elements, for example equally distributed on the circumference, are provided, which are arranged on a pitch circle formed around the axis of rotation. The screw elements extend with their longitudinal axis, for example parallel, at a distance from the axis of rotation and can be screwed in from the outside of the phase adjuster, in particular the rotor, for which purpose the screw flange has, for example, threaded bores.

The central screw in the present sense is a screw that is screwed into the end of the inner shaft, and the screw is concentric with the axis of rotation. This screw is omitted due to an inventive development of the adjustable camshaft with the features of the present Invention, there is a significantly increased space for designing the channels to establish a pressure medium connection between the bearing section and the phase adjuster. The invention provides a central channel that coincides with the axis of rotation and that opens outward or into the phase adjuster at the end of the inner shaft, so that a phase adjuster that is arranged at the end of the camshaft also has a pressure medium at least via the central channel can be fed.

The arrangement of the screw flange at the end of the inner shaft according to the invention can be carried out in different ways, the end of the inner shaft not necessarily having to terminate geometrically with the screw flange, and in the sense of the invention the end of the inner shaft only relates generally to the area of the inner shaft that is in Axis of rotation connects to the bearing section.

In the sense of an advantageous embodiment, the screw flange sits on the end of the inner shaft, so that the end extends centrally into the screw flange. For example, the screw flange is applied to the end of the inner shaft by means of a transverse compression bandage or a longitudinal press bandage, it is also conceivable that the screw flange is integrally connected to the end of the inner shaft, for example by a welding process, a soldering process or an adhesive process. It is particularly advantageous if the screw flange is centered on the end of the inner shaft with a required accuracy, so that the rotor of the phase adjuster can in turn be centered over the screw flange. There is also the possibility that the screw flange is formed in one piece with the inner shaft, so that a connection arrangement between the screw flange and the inner shaft is advantageously omitted.

A particular advantage is achieved if an annular gap is formed at least in sections between the outer shaft and the inner shaft. It is thereby achieved that the central channel forms a first oil channel and the annular gap forms a second oil channel for feeding the phase adjuster. The central channel is particularly easy to manufacture and can in a certain way be the threaded hole replace, in which the central screw can be screwed in a conventional manner. Due to the possibility according to the invention of removing the central screw, the central channel can form the first oil channel, and the annular gap between the inner shaft and the outer shaft forms a second oil channel. The annular gap and the central channel can be fed by assigned radial channels in the inner shaft and / or the outer shaft. The radial channels open into the tread of the bearing section for mounting the camshaft. According to an advantageous development of the camshaft according to the invention, at least one oil guide sleeve is introduced in the channel to form an annular gap between the outer surface of the oil guide sleeve and the inner surface of the channel, the oil guide sleeve forming a first oil channel on the inside and a second oil channel with the annular gap. This achieves the advantage that two separate oil guides are formed between the bearing section and the phase adjuster with a single central channel in the inner shaft, and the oil guide sleeve only has to be introduced into the channel in a simple manner, for example by pressing Glue or the like. The oil guide sleeve is designed, for example, as a thin-walled sheet metal component and can be clamped in the channel in a self-retaining manner, with the formation of corresponding tolerances.

A corresponding further development of the pressure medium supply to the phase adjuster provides that a first oil guide sleeve and at least one second oil guide sleeve are introduced in the channel, the oil guide sleeves lying one inside the other and in particular being arranged concentrically to the axis of rotation. Within the scope of the invention there is also the possibility of introducing more than two oil guide sleeves into the channel in order to generate separate pressure medium guides between the bearing section and the phase adjuster. In particular, there is also the possibility of including a further bearing section of the camshaft for supplying the phase adjuster with pressure medium, to which at least one, in particular two, oil channels are introduced.

With further advantage, the oil guide sleeves have different lengths and thus extend into the channel at different depths, so that the oil channels formed inside and / or between and / or outside of the oil guide sleeves with separate radial channels in the outer shaft and / or Inner shaft are fluidly connected. By means of corresponding gradations in the channel, which are formed, for example, from channel sections with different diameters, the individual oil guide sleeves can advantageously be connected in such a way that separate oil guides are achieved between the sleeves.

There is also the possibility that at least one of the oil channels is formed in sections in the screw flange, i.e. continues into this. For example, there is the possibility that an oil channel, which is formed by an annular gap between the outside of the inner shaft and the inside of the outer shaft, communicates fluidly with an oil channel and continues into the screw flange. Of course, there is also the possibility of forming a radial channel in the area on the end of the inner shaft in which the screw flange is seated. As a result, the screw flange can also be included in the pressure medium guide between the bearing section and the phase adjuster.

There are several options for centering the rotor of the phase adjuster with respect to the axis of rotation. For example, there is the possibility of centering the rotor around the axis of rotation by means of the screw flange, or there is the possibility that a resilient element is arranged between the rotor of the phase adjuster and the screw flange, via which a torque can be transmitted while compensating for position errors, the rotor itself is centered in the stator of the phase adjuster. Resilience elements are known as flex disks or the like, and there is also the possibility of providing a resilient material, for example a rubber-elastic material that forms a connection between the rotor and the screw flange. The exact centering of the rotor around the axis of rotation takes place in that it is guided in the stator of the phase adjuster. The arrangement of a resilience element means that the rotor is not overdetermined in its guidance.

According to a further variant of the adjustable camshaft, the outer shaft has an end on which a drive wheel is arranged and a stator of the phase adjuster is at least indirectly connected to the drive wheel.

It is particularly advantageous if the connection of the stator to the drive wheel has a resilience element, in particular a flexible disk. At least part of the phase adjuster, that is to say the rotor or the stator, should have a rigid, centered arrangement on the inner shaft or on the outer shaft, so that the at least one other part of the phase adjuster is guided on the centered part.

EMBODIMENT OF THE INVENTION

Fig. 1

Ein erstes Ausführungsbeispiel einer verstellbaren Nockenwelle mit einem Phasensteller, wobei ein Ölkanal durch einen zentralen Kanal in der Innenwelle gebildet ist und wobei ein weiterer Ölkanal durch einen radialen Spalt zwischen der Innenwelle und der Außenwelle gebildet ist,

Fig. 2

ein zweites Ausführungsbeispiel einer verstellbaren Nockenwelle mit einem Phasensteller, wobei eine Ölführungshülse im Kanal der Innenwelle eingebracht ist,

Fig. 3

ein Ausführungsbeispiel einer verstellbaren Nockenwelle mit einem Phasensteller, wobei eine Ölführungshülse gemäß einer alternativen Ausgestaltung in den zentralen Kanal eingebracht ist und

Fig. 4

ein Ausführungsbeispiel einer verstellbaren Nockenwelle mit einem Phasensteller, wobei zwei Ölführungshülsen konzentrisch ineinander liegend in dem Kanal in der Innenwelle eingebracht sind.

Further measures improving the invention are shown below together with an advantageous embodiment of the invention with reference to the figures. It shows:

Fig. 1

A first embodiment of an adjustable camshaft with a phase adjuster, an oil channel being formed by a central channel in the inner shaft and another oil channel being formed by a radial gap between the inner shaft and the outer shaft,

Fig. 2

2 shows a second exemplary embodiment of an adjustable camshaft with a phase adjuster, an oil guide sleeve being introduced into the channel of the inner shaft,

Fig. 3

an embodiment of an adjustable camshaft with a phase adjuster, wherein an oil guide sleeve according to an alternative embodiment is introduced into the central channel and

Fig. 4

an embodiment of an adjustable camshaft with a phase adjuster, wherein two oil guide sleeves are placed concentrically one inside the other in the channel in the inner shaft.

The Figures 1 to 4 each show embodiments of an adjustable camshaft 10, which is shown on one end side and which has an outer shaft 11 and an inner shaft 12. The inner shaft 12 is rotatable relative to the outer shaft 11, a phase adjuster 1 being arranged on the end of the camshaft 10 in order to generate the twisting movement. The phase adjuster 1 has one Stator 29 in which a rotor 17 is received. The rotor 17 can be rotated in the stator 29 about the axis of rotation 13 of the camshaft 10. The rotor 17 is connected to the inner shaft 12, and the stator 29 is connected to the outer shaft 11 via a drive wheel 28.

A screw flange 16 is attached to the end 15 of the inner shaft 12, and the rotor 17 of the phase adjuster 1 is screwed to the screw flange 16 with screw elements 19. The stator 29 is guided about the axis of rotation 13 by means of the rotor 17, and the connection of the stator 29 to the drive wheel 28 has a flexible disk 35. The flexible disk 35 forms a resilience element between the stator 29 and the drive wheel 28, wherein torques can be transmitted via the flexible disk 35.

In the area of the end 15 of the inner shaft 12, a channel 18 is introduced, which closes freely on the outside with the end face of the inner shaft 12. The channel 18 extends into a bearing section 14 of the camshaft 10 into the inner shaft 12, so that there are several options for guiding the pressure medium between the bearing section 14 and the phase adjuster 1, as shown in detail below with the respective exemplary embodiments of the figures.

Figure 1 shows a first embodiment of the camshaft 10 with a phase adjuster 1 arranged at the end, the channel 18, which coincides in its extension direction with the axis of rotation 13 of the camshaft 10, forming a first oil channel 20. In a section above the channel 18, the outer shaft 11 has an encircling radial gap with the inner shaft 12, through which a second oil channel 21 is formed. The first oil channel 18 terminates on the inside in the inner shaft 12 in radial channels 30. The second oil channel 21, which is formed by the radial gap, also runs out in radial channels 30 and opens on the outside into the screw flange 16 and continues in this.

Figure 2 shows an embodiment with a channel 18 in the inner shaft 12 of the camshaft 10, in which an oil guide sleeve 22 is inserted. The oil guide sleeve 22 forms a first oil channel 23 on the inside, and with the outside of the oil guide sleeve 22 this forms an annular gap with the inside of the channel 18 in the inner shaft 12, through which a second oil channel 24 is formed.

The respective oil channels 23 and 24 open in the area of the bearing section 14 for mounting the camshaft 10 in assigned radial channels 30. The exemplary embodiment thus shows the possibility of simply two by simply inserting an oil guide sleeve 22 into a central channel 18 in the end 15 of the inner shaft 12 separate oil channels 23 and 24 to form to control the phase adjuster 1.

Figure 3 shows an embodiment with a modified embodiment of an oil guide sleeve 22 which is introduced in the channel 18 in the inner shaft 12. The design of the oil guide sleeve 22 has end-side collars which seal against the inside of the channel 18 in the inner shaft 12. As a result, oil channels 23 and 24 which are separate from one another are also formed in a simple manner and communicate fluidically with respective radial channels 30 which open into the bearing section 14.

Finally shows Figure 4 An embodiment of an adjustable camshaft 10 with a phase adjuster 1, wherein the phase adjuster 1 is designed, for example, as a dual phase adjuster, as shown schematically by a two-part rotor 17, for example. To control the phase adjuster 1, the exemplary embodiment has two oil guide sleeves 25 and 26 arranged concentrically with respect to one another, and the oil guide sleeve 25 is inserted inside the oil guide sleeve 26 to form an annular gap. This results in a first oil channel 31 on the inside in the inner oil guide sleeve 25, a second oil channel 32 results in the annular gap between the inner oil guide sleeve 25 and the outer oil guide sleeve 26, a further oil channel 33 results in a radial gap on the outside of the outer oil guide sleeve 26 on the inside of the channel 18 and finally there is a fourth oil channel 33 in the form of an annular gap between the inside of the outer shaft 11 and the outside of the inner shaft 12. The oil channels 31, 32, 33 and 34 open into respective radial channels 30 which are located in the area of the bearing section 14 are located. The oil channels 33 and 34 open into respective continuations within the screw flange 16, so that this is also included in the oil guide.

Reference list

1

Phase adjuster

10th

camshaft

11

Outer shaft

12th

Internal shaft

13

Axis of rotation

14

Storage section

15

End of the inner shaft

16

Screw flange

17th

rotor

18th

channel

19th

Screw element

20th

Oil channel

21

Oil channel

22

Oil guide sleeve

23

Oil channel

24th

Oil channel

25th

Oil guide sleeve

26

Oil guide sleeve

27

End of the outer shaft

28

drive wheel

29

stator

30th

Radial channel

31

Oil channel

32

Oil channel

33

Oil channel

34

Oil channel

35

Flex disc

Claims (9)

1. Adjustable camshaft (10) for the valve train of an internal combustion engine, comprising an outer shaft (11) and an inner shaft (12) which extends at least in sections within the outer shaft (11) and is rotatable relative to the outer shaft (11), and having a phase shifter (1), with which at least the outer shaft (11) or the inner shaft (12) is adjustable in a phase position formed around an axis of rotation (13), and wherein the camshaft (10) comprises a bearing portion (14) for bearing the camshaft (10), via which the phase shifter (1) can be supplied with a pressurizing medium, wherein the inner shaft (12) comprises a free end (15) on which a screw flange (16) is arranged and wherein a rotor (17) of the phase shifter (1) is connected to the screw flange (16), and wherein the free end (15) of the inner shaft (12) comprises a duct (18) which coincides with the axis of rotation (13) for at least partial supply of the phase shifter (1) with the pressurizing medium, which duct (18) extends at least into the bearing portion (14) and wherein the connection of the rotor (17) to the screw flange (16) comprises at least one screw element (19), characterized in that the screw element (19) is arranged spaced apart from the axis of rotation (13).
2. Adjustable camshaft (10) according to Claim 1, characterized in that the screw flange (16) sits on the free end (15) of the inner shaft (12) so that the free end (15) extends centrally into the screw flange (16).
3. Adjustable camshaft (10) according to any one of Claims 1 and 2, characterized in that at least in sections an annular gap is formed between the outer shaft (11) and the inner shaft (12), wherein the central duct (18) forms a first oil duct (20) and the annular gap forms a second oil duct (21) to supply the phase shifter (1). (Fig. 1)
4. Adjustable camshaft (10) according to any one of the above-mentioned claims, characterized in that at least one oil-guidance sleeve (22) is incorporated in the duct (18) while forming an annular gap between the outer surface of the oil-guidance sleeve (22) and the inner surface of the duct (18), wherein the oil-guidance sleeve (22) forms an oil duct (23) on the inside and a further oil duct (24) with the annular gap. (Fig. 2 and Fig. 3)
5. Adjustable camshaft (10) according to any one of the above-mentioned claims, characterized in that a first oil-guidance sleeve (25) and at least one second oil-guidance sleeve (26) are incorporated in the duct (18), wherein the oil-guidance sleeves (25, 26) are arranged lying in one another concentrically to the axis of rotation (13).
6. Adjustable camshaft (10) according to Claim 5, characterized in that the oil-guidance sleeves (25, 26) comprise different lengths and protrude with different depths into the duct (18) so that the oil ducts (31, 32, 33, 34) formed within and/or between and/or on the outside of the oil-guidance sleeves (25, 26) are fluidically connected to radial ducts (30), which are separated from one another, in the outer shaft (11) and/or in the inner shaft (12).
7. Adjustable camshaft (10) according to any one of the above-mentioned claims, characterized in that at least one of the oil ducts (21, 24, 33, 34) is formed in sections in the screw flange (16).
8. Adjustable camshaft (10) according to any one of the above-mentioned claims, characterized in that the rotor (17) of the phase shifter (1) is centered by means of the screw flange (16) about the axis of rotation (13) or that a flexible element is arranged between the rotor (17) of the phase shifter (1) and the screw flange (16), via which flexible element a torque can be transmitted while compensating for positional errors and the rotor (17) is centered in a stator (29) of the phase shifter (1).
9. Adjustable camshaft (10) according to any one of the above-mentioned claims, characterized in that the outer shaft (11) comprises an end (27) on which a drive wheel (28) is arranged and wherein a stator (29) of the phase shifter (1) is at least indirectly connected to the drive wheel (28).

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