This application claims priority to German Application No. DE 10 2019 217 295.4 filed Nov. 8, 2019, the contents of which are hereby incorporated by reference in its entirety.
The present invention relates to a camshaft arrangement with an adjustable camshaft and with an adjuster for adjusting the camshaft. The invention relates furthermore to an internal combustion engine system with an internal combustion engine and with such a camshaft arrangement.
A camshaft usually comes into use for the actuating of valves of an internal combustion engine. For this purpose, the camshaft has cams arranged on a shaft in a rotationally fixed manner, which cams actuate respectively associated valves accordingly.
In order to increase the variability of the actuation of the valves, so-called adjustable camshafts, also designated as phase-adjustable camshafts, are known for example from DE 10 2015 224 012 A1. Such a camshaft has an outer shaft and an inner shaft arranged in the outer shaft, which inner shaft is rotatable relative to the outer shaft. The respective shaft is connected with associated cams, so that a relative rotation between the inner shaft and the outer shaft leads to a phase shift between the cams of the outer shaft and the cams of the inner shaft.
In the production and in the operation of such adjustable camshafts, it is important to precisely maintain a relative alignment of the inner shaft to the outer shaft, as offsets between the inner shaft and the outer shaft lead to increased friction and therefore in particular to an increased wear and/or a reduced lifespan. In addition, such offsets can lead to a jamming of the inner shaft on the outer shaft, which disturbs the operation of the camshaft and/or blocks an adjusting of the camshaft.
For adjusting the camshaft, i.e. for the relative rotational movement between the inner shaft and the outer shaft, usually adjusters are used, which are connected with a stator in a rotationally fixed manner, and with a rotor in a rotationally fixed manner with the inner shaft.
Such a camshaft arrangement with an adjustable camshaft and with an associated adjuster is known from DE 10 2014 206 291 A1. In DE 10 2014 206 291 A1 it is proposed to connect the rotor of the adjuster with the inner shaft via an Oldham coupling, in order to compensate offsets between the inner shaft and the outer shaft in axial and angular direction. Here, a contour or form is provided on the inner shaft, and a counter-form or counter-contour is provided on an intermediate part which is connected with the rotor in a rotationally fixed manner, for the formation of the Oldham coupling. In addition, a sleeve for supplying the camshaft arrangement with a fluid for the simultaneous actuation and lubrication penetrates axially through the intermediate part, and into the inner shaft.
A disadvantage in camshaft arrangements which are known from the prior art are the complicated construction and the continual lack of compensation of offsets between the inner shaft and the outer shaft.
The present invention is therefore concerned with the problem of indicating, for a camshaft arrangement of the above-mentioned type and for an internal combustion engine system with such a camshaft arrangement, improved or at least different embodiments, which in particular are distinguished by a simplified construction and/or by an improved compensation of offsets.
This problem is solved according to the invention by the subjects of the independent claims. Advantageous embodiments are the subject of the dependent claims.
The present invention is based on the general idea of realizing, in a camshaft arrangement with an adjustable camshaft and with an adjuster for adjusting the camshaft, an axially inserted form-fitting connection as a coupling between a rotor of the adjuster and an inner shaft of the camshaft via an already present bush for supplying the arrangement with lubricant. Therefore, an additional intermediate part for realizing the form-fitting connection between the rotor and the inner shaft can be dispensed with, and the construction of the camshaft arrangement can thus be simplified. The omission of the additional intermediate part leads, furthermore, to an improved compensation of offsets between the inner shaft and the outer shaft of the camshaft, in particular of offsets in axial direction and/or angular offsets, i.e. offsets in circumferential direction.
In accordance with the idea of the invention, the camshaft arrangement has the adjustable camshaft and the adjuster. The camshaft has an outer shaft and an inner shaft arranged rotatably in the outer shaft, wherein the outer shaft and the inner shaft are respectively connected in a rotationally fixed manner with at least one associated cam. The adjuster has a stator and the rotor. Here, the stator is connected with the outer shaft in a rotationally fixed manner. The rotor is connected in a rotationally fixed manner with the bush, by which a supply of the arrangement with lubricant takes place. The bush has here at least one channel which in operation is connected with a connection for the fluidic supply of the arrangement by lubricant, wherein the connection is provided on an outer casing of the arrangement. According to the invention, the bush has on its face side facing the inner shaft axially, a form which, with a counter-form on the inner shaft, forms the axially inserted form-fitting connection and thus the coupling. With the realizing of the coupling between the rotor and the inner shaft via the bush, therefore with a simple construction a compensation of axial offsets and/or radial offsets of the inner shaft to the outer shaft takes place.
The directions indicated in the present case refer in particular to an axis of the outer shaft. The axial direction therefore corresponds in particular to the rotation axis of the outer shaft. The angular direction corresponds accordingly to the circumferential direction surrounding the axial direction. The lateral direction corresponds accordingly to a radial direction running perpendicularly 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 axial direction, angular offsets are relative movements of the inner shaft to the outer shaft in circumferential direction and lateral offsets are relative movements of the inner shaft to the outer shaft in radial direction.
An axially inserted form-fitting connection and therefore an axially inserted coupling is to be understood here to mean a coupling having the form on the bush and the counter-form on the inner shaft, wherein the form and counter-form are inserted axially into one another and therefore produce a rotationally fixed connection between the inner shaft and the rotor, which is connected with the bush in a rotationally fixed manner.
The coupling is preferably configured as an Oldham coupling. The coupling can therefore be implemented easily and at a favourable cost.
It is also conceivable to configure the coupling as an elastomer coupling.
In addition to lubricating, the lubricant also serves for actuation, in particular for adjusting the inner shaft relative to the outer shaft. Accordingly, the lubricant is preferably a fluid. In particular, the lubricant is lubricating oil. The bush is therefore in particular an oil guide bush.
The bush is expediently arranged axially between the rotor and the inner shaft. It is preferred when the bush is connected not only in a rotationally fixed manner with the rotor, but is fixed on the rotor, so that the bush is also connected axially and laterally securely with the rotor.
The counter-form provided on the inner shaft can be formed integrally on the inner shaft. Therefore, a simple construction of the arrangement and a reliable compensation of offsets with the aid of the coupling are possible.
It is also conceivable to provide between the face side of the bush and therefore between the form and the inner shaft an intermediate part with the counter-form, which is arranged on the inner shaft.
Embodiments are preferred in which the outer shaft projects axially over the inner shaft, on the side facing the bush, with a receiving section, wherein the bush is rotatably arranged in the receiving section of the outer shaft. This means that the bush is received and rotatably arranged in the outer shaft. This leads to a compact construction of the camshaft arrangement and a simple implementation of the coupling.
Embodiments prove to be advantageous in which at least one elastic seal is arranged between a radial inner side of the outer shaft, hereinbelow also designated as outer shaft inner side, in the receiving section, and a radial outer side of the bush, hereinafter also designated as bush outer side. Therefore, a fluidic sealing of the receiving region is achieved. In particular, the flowing of the lubricant from the receiving region is thus prevented or at least reduced. It is preferred here if at least two seals, spaced apart axially with respect to one another, are provided. An axial flowing of the lubricant in both axial directions is thus at least reduced.
It is preferred if at least one of the at least one seals is arranged and received in an associated, radially open outer groove in the outer shaft inner side or respectively in the bush outer side, advantageously in the bush outer side.
It is preferred here when the seal is arranged radially between the bush outer side and the associated slide ring.
Advantageously, an associated slide ring is arranged radially between at least one of the at least one seals, preferably the respective seal, and the outer shaft inner side or the bush outer side. Preferably, the slide ring is arranged radially between the associated seal and the outer shaft inner side. The slide ring serves here for the protection of the seal during relative movements, in particular rotations, between the outer shaft and the inner shaft. Thus, in particular, the transmission of shearing forces to the seal is prevented or at least reduced. Consequently, damage to the seal is reduced, so that a sealing takes place with the seal for a longer duration.
At least one of the at least one slide rings is advantageously a slotted slide ring, i.e. interrupted in circumferential direction. The slide ring can therefore be mounted in particular in a simplified manner. Rectangular rings are also conceivable.
The elastic seal can be configured basically in any desired manner. In particular, the seal is a ring seal. This leads to a homogeneous and/or improved sealing effect. Embodiments are also conceivable in the form of slide- or respectively rectangular rings with reduced adhesion- and sliding friction coefficient for an improved response behaviour and reduced losses in operation. In particular PTFE-coated rings are advantageous for this.
With the at least one seal and the coupling, the bush is advantageously arranged radially freely in the outer shaft. This means in particular to be spaced apart more radially between the bush to the outer shaft and/or that a bearing of the bush in the outer shaft can be dispensed with. Therefore, the outer shaft and/or the bush can be produced in a simplified manner. In particular, the outer shaft can be produced radially on the inner side and/or the bush can be produced radially on the outer side with higher tolerances. In particular, a fine processing of the outer shaft inner side can be dispensed with. In addition, in this way a simpler relative positioning of the rotor to the inner shaft is possible. In particular, in this way an exact lateral positioning of the rotor to the inner shaft can be dispensed with.
Alternatively or additionally, the rotor can be rotatably mounted via a radially exterior outer side of the outer shaft, hereinbelow also designated as outer shaft outer side. In particular, the rotor can be rotatably mounted exclusively via the outer shaft outer side. This leads in particular to the fact that a separate processing of the outer shaft inner side can be dispensed with, so that the outer shaft as a whole can be produced at a more favourable cost. In particular, it is thus possible to produce the outer shaft inner side with increased tolerances. At the same time, via the rotatably mounting of the rotor on the outer shaft outer side, a compensation and/or reduction of lateral offsets between the inner shaft and the outer shaft is achieved.
The mounting of the rotor on the outer shaft outer side is advantageously realized in such a way that the outer shaft has an axial projection which penetrates into the adjuster, in particular projects over the bush in axial direction. Here, the rotor is rotatably mounted on the outer shaft outer side of the projection. This leads in particular to the mounting of the rotor on the outer shaft being implemented in an installation-space-saving and efficient manner. In particular, in this way, owing to the vicinity of the rotor to the projection, a simple mounting of the rotor on the outer shaft can take place.
The rotationally fixed connection of the rotor with the bush, in particular the fixing of the rotor on the bush, is preferably realized via a pin which can be a component part of a screw. In particular, the pin can have an external thread which forms a screw connection with an internal thread of the bush. Here, a screw head or a nut of the screw connection can act upon the rotor axially against the bush, in such a way that a rotationally fixed connection of the rotor with the bush is provided.
The pin has advantageously in the interior a cavity, which is also designed hereinbelow as pin cavity. It is preferred here if the pin cavity is fluidically connected with the interior of the bush, in particular a cavity formed in the interior of the bush, designated hereinbelow also as bush cavity. In this way, it is possible in particular to realize the feeding and the discharging of the lubricant via the bush and the pin.
The camshaft arrangement expediently has a drive wheel which serves for driving the camshaft. The drive wheel is expediently connected with the stator in a rotationally fixed manner. The drive wheel can be driven in an associated system with an internal combustion engine, hereinbelow also designated internal combustion engine system, by a crankshaft of the internal combustion engine. Here, the drive wheel can be, in particular, a spur wheel.
It is conceivable here to form the drive wheel and the stator in a single part. This means in particular that the drive wheel and the stator can be fixed to one another via a materially bonded connection or a force-fitting connection.
In addition, it is conceivable to form the drive wheel and the stator in a single piece. In particular, the drive wheel and the stator can be produced jointly, for example by sintering.
An easy centring of the stator to the outer shaft can be achieved when the stator is connected directly or indirectly with the receiving section of the outer shaft. Thus, an easy centring of the adjuster relative to the outer shaft and/or to the inner shaft also takes place.
For centring the adjuster, alternatively or additionally at least one centring collar can be provided, for example on the drive wheel.
The bush can have, as mentioned above, a bush cavity which in particular serves for supplying the arrangement with the lubricant. The bush cavity is expediently closed on the side axially facing the form and therefore on the side axially facing the inner shaft.
The bush preferably has at least two channels, spaced axially with respect to one another, which are connected respectively fluidically with the bush cavity, wherein the channels are arranged axially between two slide rings. This leads to an improved mounting of the bush and therefore of the rotor in the inner shaft. It is advantageous here if for the respective slide ring an associated seal of the described type, therefore an elastic seal in radial direction, is provided. Thus in particular the region which is flowed through fluidically in operation is sealed in an improved manner.
It is advantageous if the bush in addition has at least two such channels spaced apart from one another in circumferential direction. Consequently in operation an improved supplying of the arrangement with lubricant takes place.
It shall be understood that in addition to the camshaft arrangement also an internal combustion engine system with such a camshaft arrangement belongs to the scope of this invention. The internal combustion engine system comprises, in addition to the camshaft arrangement, the internal combustion engine which has at least two valves which are actuated in operation by the cams of the camshaft.
Further important features and advantages of the invention will emerge from the subclaims, from the drawings and from the associated figure description with the aid of the drawings.
It shall be understood that the features mentioned above and to be explained further below are able to be used not only in the respectively indicated combination, but also in other combinations or in isolation, without departing from the scope of the present invention.
Preferred example embodiments of the invention are illustrated in the drawings and are explained in further detail in the following description, wherein the same reference numbers refer to identical or similar or functionally identical components.
There are shown, respectively schematically
A camshaft arrangement 1, as shown for example in
As can be seen from
As can be seen in particular from
In the example embodiments which are shown, the coupling 21 is configured as an Oldham coupling 22.
As can be seen in particular from
As can be seen from
As can be seen from
As can be seen in particular from viewing
In
As can be seen in particular from
The seals 32 and the coupling 21 allow the bush 14 to be positioned radially freely in the outer shaft 4. A mounting of the bush 14 in the outer shaft 4 can thus be dispensed with.
Another example embodiment of the camshaft arrangement 1 is shown in
The respective camshaft arrangement 1 compensates via the coupling 21 an axial and angular offset between the inner shaft 5 and the outer shaft 4. Through the mounting of the rotor 12 and of the bush 14 on the outer shaft, in addition a lateral offset is compensated between the inner shaft 5 and the outer shaft 4. In addition, in this way the respective camshaft arrangement 1 is able to be produced in a compact and simple manner.
Number | Date | Country | Kind |
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102019217295.4 | Nov 2019 | DE | national |