DE102020129568A1 - camshaft arrangement - Google Patents

Abstract

The present invention relates to a camshaft arrangement (1) which has an adjustable camshaft (3) which has an outer shaft (4) and an inner shaft (5) which is rotatably arranged in the outer shaft (4), and an adjuster (10) which a stator (11) connected in a rotationally fixed manner to the outer shaft (4) and a rotor (12) connected in a rotationally fixed manner to the inner shaft (5). The rotor (12) is connected to the inner shaft (5) in the manner of an axially plugged-in coupling (21) via a bushing (14) for the fluidic supply of the camshaft arrangement (1) with a lubricant. One in terms of robustness and control quality The improved camshaft arrangement (1) results from the fact that the coupling (21) is designed as a curved tooth coupling and connecting sections (22, 23) designed as coupling hubs and provided with curved toothed rims (25, 26) on the bushing (14) and inner shaft (5 ) and a connecting sleeve (24) with straight-toothed internal teeth (27). The invention also relates to an internal combustion engine system (2) with such a camshaft arrangement (1).

Description

The present invention relates to a camshaft arrangement with an adjustable camshaft and an adjuster for adjusting the camshaft. The invention also relates to an internal combustion engine system with an internal combustion engine and such a camshaft arrangement.

A camshaft is usually used to actuate valves of an internal combustion engine. For this purpose, the camshaft has cams which are arranged in a rotationally fixed manner on a shaft and which correspondingly actuate associated valves.

In order to increase the variability of the actuation of the valves, so-called adjustable camshafts, also called phase-adjustable camshafts, for example from DE 10 2015 224 012 A1 , famous. Such a camshaft has an outer shaft and an inner shaft which is arranged in the outer shaft and can be rotated relative to the outer shaft. Each shaft is connected to associated cams such that relative rotation between the inner shaft and the outer shaft results in a phase shift between the cams on the outer shaft and the cams on the inner shaft.

In the manufacture and operation of such adjustable camshafts, it is important to precisely maintain a relative alignment of the inner shaft to the outer shaft, since misalignments between the inner shaft and the outer shaft lead to increased friction and thus in particular to increased wear and/or a reduced service life. In addition, such offsets can lead to the inner shaft jamming on the outer shaft, which disrupts the operation of the camshaft and/or blocks adjustment of the camshaft.

To adjust the camshaft, i. H. for the relative rotational movement between the inner shaft and the outer shaft, adjusters are usually used, which are non-rotatably connected to the outer shaft with a stator and are non-rotatably connected to the inner shaft with a rotor.

Such a camshaft arrangement with an adjustable camshaft and an associated adjuster is from DE 10 2014 206 291 A1 famous. In the DE 10 2014 206 291 A1 it is proposed to connect the rotor of the adjuster to the inner shaft via an Oldham coupling in order to compensate for offsets between the inner shaft and the outer shaft in the axial and angular directions. In this case, a contour or shape is provided on the inner shaft and a counter-shape or counter-contour is provided on an intermediate piece which is non-rotatably connected to the rotor to form the Oldham coupling. In addition, a sleeve for supplying the camshaft arrangement with a fluid for simultaneous activation and lubrication penetrates axially through the adapter and into the inner shaft.

The disadvantages of camshaft arrangements known from the prior art are the complicated structure and the continuing lack of compensation for offsets between the inner shaft and the outer shaft.

The present invention is therefore concerned with the task of specifying improved or at least different embodiments for a camshaft arrangement of the type mentioned above and for an internal combustion engine system with such a camshaft arrangement, which is characterized in particular by a simplified structure and/or an improved compensation of mark offsets.

According to the invention, this object is achieved by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

According to the idea of the invention, the camshaft arrangement has the adjustable camshaft and the camshaft adjuster. The camshaft has an outer shaft and an inner shaft rotatably arranged in the outer shaft, the outer shaft and the inner shaft each being connected in a rotationally fixed manner to at least one associated cam. The camshaft adjuster has a stator and the rotor. Here, the stator is non-rotatably connected to the outer shaft. The rotor is non-rotatably connected to the inner shaft via an axially plugged-in coupling, so that a rotation of the rotor relative to the stator leads to a relative rotation of the inner shaft to the outer shaft. The rotor is connected in a torque-proof manner to a bushing, with which the arrangement is supplied with lubricant. The bush has at least one channel which, during operation, is connected to a connection for fluidly supplying the arrangement with lubricant, the connection being provided on an outer casing of the arrangement.

According to the invention, the coupling is designed as a curved-tooth coupling and has connecting sections on the bushing and inner shaft, designed as coupling hubs and provided with curved toothed rims, as well as a connecting sleeve with straight-toothed internal teeth.

With the implementation of the curved tooth coupling between the rotor and the inner shaft via the bushing, axial offsets and/or radial offsets of the inner shaft relative to the outer shaft are compensated with a simple construction.

The curved tooth coupling is easy to assemble and, thanks to the low backlash, enables high control quality, while at the same time enabling the transmission of a high nominal torque. The low level of wear also results in a robust clutch.

The directions specified here relate in particular to an axis of the outer shaft. The axial direction therefore corresponds in particular to the axis of rotation of the outer shaft. Accordingly, the angular direction corresponds to the circumferential direction surrounding the axial direction. Accordingly, the lateral direction corresponds to a radial direction running perpendicular to the axial direction. Accordingly, axial offsets of the inner shaft to the outer shaft are relative displacements of the inner shaft to the outer shaft in the axial direction, angular offsets are relative movements of the inner shaft to the outer shaft in the circumferential direction and lateral offsets are relative movements of the inner shaft to the outer shaft in the radial direction.

The connecting sections can preferably each be provided as projections of the bushing and the inner shaft with a reduced outside diameter. The connection sections are thus formed integrally on the bushing and the inner shaft. Thus, a simple construction of the arrangement and a reliable compensation of misalignments with the help of the clutch are easily possible.

Alternatively, the connecting sections can be connected to the bushing and the inner shaft in a non-positive and/or positive manner. The clutch geometries are thus advantageously designed as separate components.

Embodiments are preferred in which the outer shaft protrudes axially beyond the inner shaft on the side facing the bushing with a receiving section and the bushing is arranged rotatably in the receiving section of the outer shaft. That is, the bushing is accommodated in the outer shaft and is rotatably arranged. This leads to a compact construction of the camshaft arrangement and a simple implementation of the clutch.

According to an advantageous embodiment of the invention, the socket on the side facing away from the inner shaft can protrude axially beyond the receiving section with a flange section with an enlarged outer diameter, the rotor being arranged coaxially on the flange section and being connected to it in a non-positive and/or material connection. In this way, offsets or misalignments in this regard can be ruled out.

Embodiments have proven to be advantageous in which at least one elastic seal is arranged between a radial inside of the outer shaft, hereinafter also called outer shaft inside, in the receiving section and a radial outside of the bushing, hereinafter also called bushing outside. A fluidic seal of the receiving area is thus achieved. In particular, this prevents or at least reduces the flow of lubricant out of the receiving area. It is preferred here if at least two seals are provided which are spaced apart axially from one another. An axial flow of the lubricant in both axial directions is thus at least reduced.

It is preferred if at least one of the at least one seal is arranged and accommodated in an associated, radially open outer groove in the inside of the outer shaft or the outside of the bushing, advantageously in the outside of the bushing.

Advantageously, an associated sliding ring can be arranged radially between at least one of the at least one seal, preferably the respective seal, and the inside of the outer shaft or the outside of the bush. The slide ring is preferably arranged radially between the associated seal and the inside of the outer shaft. The slide ring serves to protect the seal during relative movements, in particular rotations, between the outer shaft and the inner shaft. In this way, in particular, the transfer of shearing forces to the seal is avoided or at least reduced. As a result, damage to the gasket is reduced so that the gasket seals for a longer period of time.

At least one of the at least one seal rings is advantageously a slotted seal ring, ie one that is interrupted in the circumferential direction. The slide ring can thus be installed in a particularly simplified manner. Rectangular rings are also conceivable.

In principle, the elastic seal can have any configuration. In particular, the seal is a ring seal. This leads to a homogeneous and/or improved sealing effect. Designs in the form of sliding or rectangular rings with reduced static and sliding friction coefficients for improved response behavior and reduced losses during operation are also conceivable. PTFE-coated rings are particularly advantageous for this.

With the at least one seal and the clutch, the bushing is advantageously arranged radially freely in the outer shaft. This means in particular that the bushing can be spaced radially from the outer shaft and/or the bushing does not need to be mounted in the outer shaft. The outer shaft and/or the bushing can thus be manufactured in a simplified manner. In particular, the outer shaft can be manufactured radially on the inside and/or the bush can be manufactured radially on the outside with higher tolerances. In particular, fine machining of the inside of the outer shaft can be omitted. In addition, a simpler positioning of the rotor relative to the inner shaft is possible in this way. In particular, an exact lateral positioning of the rotor to the inner shaft can be omitted in this way.

In addition to lubricating, the lubricant is preferably also used for actuation, in particular for adjusting the inner shaft relative to the outer shaft. Accordingly, the lubricant is preferably a hydraulic fluid. In particular, the lubricant is hydraulic oil. According to an advantageous embodiment of the invention, the bushing is an oil guide bushing.

The socket is preferably designed as a valve housing for a central valve. The central valve is used to control the camshaft adjuster and is arranged coaxially in the camshaft adjuster in a compact manner. The central valve can be designed to supply lubricant to the clutch and/or the camshaft. The valve housing thus serves several functions. A separate attachment of the rotor, for example by a central screw, is not required. Elastic seals between the valve housing and the inside of the outer shaft preferably ensure sealing of the central valve connections.

It goes without saying that, in addition to the camshaft arrangement, an internal combustion engine system with such a camshaft arrangement also belongs to the scope of this invention. In addition to the camshaft arrangement, the internal combustion engine system includes the internal combustion engine, which has at least two valves which are actuated during operation by the cams of the camshaft.

Further important features and advantages of the invention result from the dependent claims, from the drawings and from the associated description of the figures with reference to the drawings.

It goes without saying that the features mentioned above and those still to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description, with the same reference symbols referring to identical or similar or functionally identical components.

• 1 eine isometrische einer Nockenwellen-Anordnung,
• 2 eine Explosionsdarstellung der Nockenwellen-Anordnung gemäß 1,
• 3 einen vergrößerten Ausschnitt X der Nockenwellen-Anordnung gemäß 2,
• 4 die Nockenwellen-Anordnung gemäß 1, teilweise im Längsschnitt,
• 5 einen vergrößerten Ausschnitt Y der Nockenwellen-Anordnung gemäß 4,
• 6 einen Schnitt C - C durch die Nockenwellen-Anordnung gemäß 4.

Show it, each schematically

• 1 an isometric of a camshaft assembly,
• 2 an exploded view of the camshaft assembly according to 1 ,
• 3 according to an enlarged section X of the camshaft arrangement 2 ,
• 4 the camshaft arrangement according to 1 , partly in longitudinal section,
• 5 according to an enlarged section Y of the camshaft arrangement 4 ,
• 6 a section C - C through the camshaft assembly according to 4 .

A camshaft assembly 1, as for example in the 1 until 6 is shown, is used in an internal combustion engine system, which is otherwise not shown, to actuate valves, which are not shown, of an internal combustion engine, which is not shown. The camshaft arrangement 1, which in 1 isometric and in 2 is shown as an isometric exploded view, according to in 4 longitudinal section shown an adjustable camshaft 3 with a hollow outer shaft 4 and an inner shaft 5, which is rotatably arranged in the outer shaft 4. The outer shaft 4 can be rotated about an axis of rotation 6 which corresponds to an axial direction 7 . In an optimal arrangement, the inner shaft 5 and the outer shaft 4 are arranged coaxially, ie the inner shaft 5 and the outer shaft 4 have the same axis of rotation 6 . At least one associated cam, with which a valve of the internal combustion engine can be actuated, is attached in a rotationally fixed manner to the outer shaft 4 . In addition, an associated cam 8 is attached to the inner shaft 5 in a rotationally fixed manner via a bolt 38, with which a valve of the internal combustion engine can be actuated. The camshaft arrangement 1 can also have a drive wheel 9 which is connected in a torque-proof manner to the outer shaft 4 and thus rotates the outer shaft 4 . For rotating the inner shaft 5 relative to the outer shaft 4 and thus for adjusting the camshaft 3, the camshaft arrangement 1 has a 4 Camshaft adjuster 10 shown in section. This has a non-rotatably connected to the outer shaft 4 stator 11, which for example via screw connections or cohesively connected to the drive wheel 9 in a rotationally fixed manner. The drive wheel 9 can be a toothed wheel or a belt wheel and, according to an exemplary embodiment that is not shown, can be formed in one piece with the stator 11 . The camshaft adjuster 10 also has a rotor 12 which is connected in a rotationally fixed manner to the inner shaft 5 and which can be rotated relative to the stator 11 , this taking place via a corresponding rotation of the rotor 12 in relation to the stator 11 .

As 4 can be removed, the camshaft assembly 1 has a bushing 14 which is used to supply the camshaft assembly 1 with a lubricant or hydraulic fluid, in particular hydraulic oil. In addition to lubricating the camshaft arrangement 1, the lubricant is also used for actuation, in particular for moving the inner shaft 5 relative to the outer shaft 4. For this purpose, the bushing 14 is fluid during operation via at least one connection 15 provided on an outer shell of the camshaft arrangement 1 supplied with the lubricant, with the connection 15 serving to supply the lubricant. Another connection 16 on the outer shell is provided for discharging the lubricant.

The rotor 12 is non-rotatably connected to the inner shaft 5 via the bushing 14 which is arranged axially between the rotor 12 and the inner shaft 5 . In this case, a clutch 21 is provided for the non-rotatable connection of the rotor 12 with the inner shaft 5, which in the 3 and 5 in an enlarged section of the 2 respectively. 4 is shown.

Via the clutch 21, which is described in more detail below, a rotation of the rotor 12 relative to the stator 11 leads to a relative rotation of the inner shaft 5 to the outer shaft 4. According to the invention, the clutch 21 is designed as a curved tooth clutch and has clutch hubs with arcuate ring gears 25, 26 provided connecting sections 22, 23 on the bushing 14 and inner shaft 5 and a connecting sleeve 24 with a straight-toothed internal toothing.

How in particular 5 it can be seen that the connecting sections 22, 23 are each provided as projections of the bushing 14 and the inner shaft 5 that have a reduced outside diameter. As an alternative to this integral design of the connecting sections 22, 23, it would be conceivable to design the connecting sections 22, 23 as separate components and to connect them to the bushing 14 and the inner shaft 5 in a non-positive and/or positive manner.

3 shows the details of the clutch 21 in an enlarged view. As can be seen, the connecting sections 22, 23 are provided as coupling hubs with narrow sprockets 25, 26, the tooth flanks of which are aligned axially with respect to the axis of rotation 6 and are arcuate. The connecting sleeve 24 with the straight-toothed inner toothing 27 forms the counterpart, which transmits the torque from the bushing 14 to the inner shaft 5 . The lubricant in the clutch is thrown outwards by centrifugal force during operation. Since the clutch 21 has only a small amount of play, the lubricant, which is provided by the connection 15 and the bushing 14 of the clutch 21, forms a shock-absorbing oil film between the force-transmitting tooth flanks, especially when the direction of rotation changes, so that the wear on the clutch 21 is reduced can.

The curved tooth coupling 21 described is easy to assemble and enables the compensation of radial, axial and angular offsets between the inner shaft 5 and the bushing 14. Thanks to the small amount of play, high control quality is possible, with the coupling 21 simultaneously enabling the transmission of a high nominal torque. Due to the low level of wear, a robust clutch 21 is also obtained.

The outer shaft 4 protrudes axially beyond the inner shaft 5 on the side facing the bushing 14 with a receiving section 28 , the bushing 14 being rotatably arranged in the receiving section 28 of the outer shaft 4 . i.e. the bushing 14 is accommodated in the outer shaft 4 and is rotatably arranged, as a result of which a compact construction of the camshaft arrangement 1 is achieved. On the side facing away from the inner shaft 5, however, the bushing 14 protrudes beyond the receiving section 28 with a flange section 40 with an enlarged outer diameter, on which the rotor 12 is arranged coaxially and is connected to it in a non-positive and/or material connection.

Furthermore, at least one, preferably several, elastic, annular seals 29 are arranged between a radial inner side of the outer shaft 4, also referred to below as the outer shaft inner side, in the receiving section 28 and a radial outer side of the bushing 14, also referred to below as the outer side of the bushing, so that a Fluidic sealing of the receiving area 28 is achieved. In addition, a sliding ring can be arranged radially between the outside of the bushing and the seal 29 . For secure positioning of the seals 29, the bushing 14 can have corresponding annular recesses or radially open outer grooves in the outside of the bushing.

As already explained above, the bushing 14 serves to supply the camshaft arrangement 1 with lubricant, in particular hydraulic oil, which can be supplied and discharged via the connections 15, 16.
In addition to this function of the bushing 14 as an oil guide bushing, it can also be provided as a valve housing for a central valve 20 .

The stator 11 of the hydraulic camshaft adjuster 10 has webs 30 projecting radially inwards. A vane, not shown in detail, of the rotor 12 is arranged around the circumference between the webs 30 in each case. The blades of the rotor 12 are mounted on a rotor hub 31 which is connected to the inner shaft 5 in a rotationally fixed manner. For this purpose, the rotor hub 31 is connected to the socket 14 of the central valve 20 which is used to control the camshaft adjuster 10 .

Between the webs 30 are pressure chambers 32 that can be acted upon by the hydraulic oil, which are divided by the vanes into pressure chambers that act in opposite directions, with the oil as hydraulic fluid regulating the pressure chambers 32 with the aid of the central valve 20 via channels 17, 33 formed in or on the rotor hub 31 applied. The drive wheel 9 or a cover 34 seals off the pressure chambers 42 from the environment in the axial direction.

During operation of the internal combustion engine, the pressure chambers 32 are continuously filled with hydraulic fluid so that the rotor 12 and the stator 11 are relatively rigidly connected to one another. In order to change the angular position between the inner shaft 5 and the outer shaft 4, the rotor 12 is rotated relative to the stator 11. For this purpose, depending on a desired direction of rotation, the pressure chambers 32 are loaded or relieved by supplying hydraulic fluid and by discharging hydraulic fluid into a tank, not shown in detail.

The central valve 20 has the hollow-cylindrical bushing 14 as the valve housing, which accommodates a piston 35 in an axially displaceable manner. The piston 35 is designed for axial movement in the direction of a longitudinal axis 36 , which is designed to be coaxial with the axis of rotation 6 of the camshaft arrangement 1 , and is operatively connected to an electromagnetic actuator 37 via a plunger 39 . The piston 35 is prestressed in the direction of the actuator 37 by means of a spring 47, the spring 47 bearing against a spring plate 48 fastened in the bushing 14 and against a piston end.

The bushing 14 has a plurality of radial bushing passages/channels 41, 44, 45, 46 which represent connections for the central valve 20. A first socket passage or channel 41, which is connected to the port 15, represents a supply port P and is surrounded by a screen 42 on a socket outside. A check valve 43 is arranged on the inside of the bushing in the region of the channel 41, which prevents the hydraulic fluid from flowing back in the direction of the supply connection P.

A second socket passage/channel 44 , which forms a tank connection T, also adjoins in the axial direction. The hydraulic fluid can be led out of the camshaft arrangement 1 via the tank connection T and the connection 16 connected thereto.

Working connections A and B, which are assigned to the various pressure chambers 32 of the camshaft adjuster 10, are formed by a third and a fourth bush passage 45, 46, with the fourth bush passage 46 being arranged in the area of the flange section 40. Depending on the position of the piston 35, which is hollow for the flow of hydraulic fluid, the working ports A, B are connected to the supply port P or the tank port T.

As already mentioned, the clutch 21 is lubricated via the connection 15, via which the supply connection P is also fed with hydraulic fluid. For this purpose, the connection 15 is connected to the usual lubricant circuit of the internal combustion engine and is supplied with lubricant with the aid of a feed pump.

A portion of the hydraulic fluid flows away as leakage fluid between the piston 35 and the inside of the bush in the direction of the spring plate 48, which has an opening 49 on the end face for this purpose.

QUOTES INCLUDED IN DESCRIPTION

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

Patent Literature Cited

• DE 102015224012 A1 [0003]
• DE 102014206291 A1 [0006]

Claims (10)

Camshaft arrangement (1) with an adjustable camshaft (3) and a camshaft adjuster (10) for adjusting the camshaft (3), wherein - the camshaft (3) has an outer shaft (4) and an inner shaft rotatably arranged in the outer shaft (4). (5), each of which is non-rotatably connected to at least one associated cam (8), - the camshaft adjuster (10) has a stator (11) non-rotatably connected to the outer shaft (4) and a rotor (12), - the rotor ( 12), which is non-rotatably connected to the inner shaft (5) via an axially plugged-in coupling (21), so that a rotation of the rotor (12) relative to the stator (11) results in a relative rotation of the inner shaft (5) to the outer shaft (4 ) leads, - a bushing (14) is non-rotatably connected to the rotor (12) and has at least one duct (41) for supplying the camshaft arrangement (1) with a lubricant, which during operation for supplying lubricant with a Outer shell of the camshaft assembly (1) v envisaged connection (15) is fluidically connected, characterized in that the coupling (21) is designed as a curved tooth coupling and connecting sections (22, 23) designed as coupling hubs and provided with curved toothed rims (25, 26) on the bush (14) and inner shaft ( 5) and a connecting sleeve (24) with straight-toothed internal teeth (27). Camshaft arrangement (1) according to claim 1 , characterized in that the connecting sections (22, 23) are each provided as projections of the bushing (14) and the inner shaft (5) with a reduced outside diameter. Camshaft arrangement (1) according to claim 1 , characterized in that the connecting sections (22, 23) are each non-positively and/or positively connected to the bushing (14) and the inner shaft (5). Camshaft arrangement (1) according to claim 1 , 2 or 3 , characterized in that the outer shaft (4) protrudes axially beyond the inner shaft (5) on the side facing the bushing (14) with a receiving section (28) and the bushing (14) is rotatably arranged in the receiving section (28). Camshaft arrangement (1) according to claim 4 , characterized in that the bushing (14) on the side facing away from the inner shaft (5) protrudes axially beyond the receiving section (28) with a flange section (40) enlarged in outside diameter, the rotor (12) being arranged coaxially on the flange section (40). and is connected to it in a non-positive and/or cohesive manner. Camshaft arrangement (1) according to claim 4 or 5 , characterized in that at least one elastic seal (29) is arranged radially between an outer shaft inner side of the receiving section (28) and a bushing outer side of the bushing (14). Camshaft arrangement (1) according to one of the preceding claims, characterized in that the bush (14) is designed as an oil guide bush. Camshaft arrangement (1) according to one of the preceding Claims 1 until 6 , characterized in that the socket (14) is designed as a valve housing for a central valve (20). Camshaft arrangement (1) according to claim 8 , characterized in that the central valve (38) is designed to supply lubricant to the clutch (21) and/or the camshaft (3). Internal combustion engine system (2) with an internal combustion engine, which has at least two valves, and with a camshaft arrangement (1) according to one of Claims 1 until 9 to operate the valves.

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