Patent Application
20200095904
The following documents are incorporated herein by reference as if fully set forth: German Patent Application No. 10 2018 123 178.4, filed Sep. 20, 2018.
A camshaft adjusting system for a first camshaft and a second camshaft which are arranged concentrically with respect to one another, with the second camshaft being arranged within the first camshaft. A hydraulic camshaft adjuster of the vane cell type is set up to adjust the first camshaft, and an electric camshaft adjuster is set up to adjust the second camshaft. Furthermore, a camshaft adjusting unit is provided having the camshaft adjusting system and two camshafts which are arranged concentrically with respect to one another.
Camshaft adjusting systems for two camshafts which are arranged concentrically with respect to one another are already known from the prior art. Here, for example, there are differences in the type of the respective adjusters which can be both electric and hydraulic.
Thus, for example, EP 3 141 711 A1 discloses a double camshaft adjuster which is used for an internal combustion engine which has a crankshaft and a valve train which has a first and a second group of cams, it being possible for the phase of the cams in each group to be adapted relative to the phase of the crankshaft independently of the phase of the cams of the other group. The double adjuster has an electric first adjuster for actuating the first group of cams and a hydraulic second adjuster for actuating the second group of cams. The axially coupled construction which is disclosed here between the hydraulic and the electric adjuster is very intensive in terms of installation space, however.
US 2014/0190435 A1 discloses a variable camshaft adjuster with a first fluid transfer arrangement with a fluid transfer sleeve and/or with a multiplicity of pressurized fluid passages, and a fluid transfer plate with a multiplicity of pressurized fluid passages. Each passage extends in order to be connected fluidically to a corresponding circumferentially arranged annular groove segment section for the selective connection to a camshaft adjuster of the vane cell type in a manner which is dependent on an angular orientation of the fluid transfer sleeve during the rotation. Each passage which extends from a corresponding centrally arranged port is connected fluidically to a radially extending passage section and to an arcuately extending passage section.
US 2013/0306011 A1 discloses a variable camshaft adjuster for an internal combustion engine with a concentric camshaft, which camshaft adjuster includes a stator with a rotational axis. An outer rotor can rotate independently relative to the rotational axis of the stator. A combination of an external vane and a cavity can be associated with the external rotor, in order to define first and second external variable volume working chambers. A radially inner rotor can rotate relative to the rotational axis and independently of both the stator and the external rotor. A combination of an external vane and a cavity can be associated with the internal rotor, in order to define first and second internal variable volume working chambers. If the first and second, internal and external chambers are connected selectively to a source for pressurized fluid, the phase orientation of the external and internal rotors relative to one another and in relation to the stator is adjustable.
It is a disadvantage of the previously known systems that the angular adjustment of the first and the second camshaft (also called the intake and exhaust camshafts or the inner and outer shafts) via the adjusting system are dependent on one another. As a result, an increased adjusting range of the inner shaft for counteracting the outer shaft is required. This can firstly be implemented hydraulically only to a limited extent, and secondly the counteraction can prove intensive in terms of time and can be accompanied by a relatively great control fault.
It is an object to avoid or at least mitigate the disadvantages from the prior art and, in particular, to provide a system which is favorable in terms of costs and installation space and, in particular, solves the disadvantages of the great adjusting range of the inner shaft, the time-intensive counteraction of the inner shaft and the fault-prone control accuracy.
This object is achieved by virtue of the fact that the second camshaft is supported in the axial direction on a stator of the hydraulic camshaft adjuster, via a flex pot and a front cover. Furthermore, the object is also achieved by way of a camshaft adjusting unit having a camshaft adjusting system and two camshafts which are arranged concentrically with respect to one another. Axial fixing of the second adjusting shaft/camshaft is therefore performed.
In the case of said design, the use of a flanged bushing and a separate output internal gear can be dispensed with, as a result of which the overall design can be realized in a particularly flat and less expensive manner.
Advantageous embodiments are described below and in the claims.
For instance, it is advantageous if the front cover which is fastened to the stator of the hydraulic camshaft adjuster and closes the hydraulic camshaft adjuster on a side which faces away from the camshafts has an internal toothing system for supporting the flex pot which is attached to the second camshaft and is equipped to transmit torque from the electric camshaft adjuster.
It is also advantageous here if the front cover is an integral/single-piece/single-material constituent part of the stator or a component which is separate from the latter. If the front cover is an integral constituent part of the stator, connecting elements can also be dispensed with, such as screws. Depending on the installation space, it can also be advantageous, however, if the front cover is configured as a component which is separate from the stator, in order to simplify the assembly, for example.
Furthermore, it is advantageous if the front cover is divided into a stop component and a toothing component which is separate from the latter, or the front cover has both a stop and a toothing section. Here, it is also dependent on the available installation space whether the two functions are integrated into one component and are divided among two separate components, in order to simplify the assembly, for example.
Here, one possible embodiment provides that the stop component or the stop has a shoulder which prevents an axial movement of the flex pot and/or an anti-friction bearing outer shell in the flex pot in the direction of an electric motor of the electric camshaft adjuster, that is to say away from the camshafts. In this way, the stop component ensures that a displacement in the axial direction is limited or prevented.
Furthermore, it has been shown to be advantageous if an adapter part for conducting oil is arranged in the axial direction between the rotor of the hydraulic camshaft adjuster and the flex pot. This adapter part has inner channels and a ring channel on the external diameter, via which the feed and discharge of the control oil into/out of the pressure chambers of the hydraulic adjuster are made possible.
Moreover, it is advantageous if the stop component engages around the front cover. This results in a simple assembly possibility, in a similar manner to a spring cover.
One particularly advantageous embodiment provides here that a frictionally locking connection, for instance a press fit, is configured between the stop component and the front cover.
It is advantageous if the flex pot is connected via an intermediate part to the second camshaft. This makes more precise positioning and/or centering of the flex pot with regard to the camshaft possible.
Furthermore, it has been shown to be advantageous if the electric camshaft adjuster is connected to one of the camshafts by an Oldham coupling/diametrical slot coupling. That is to say, the coupling is configured as a non-switchable, torsionally rigid coupling which can compensate for a radial offset of two parallel shafts. An Oldham coupling is known per se from the prior art, for which reason it is not described in greater detail at this point.
In other words, the adjusting ranges for the outer shaft and for the inner shaft are decoupled by way of the use of an internally toothed front cover of the hydraulic camshaft adjuster as an internal gear for the flex pot which is connected in a torque-proof manner to the inner shaft of the concentric camshaft. The axial mounting of the adjusting shaft takes place either via a stepped portion on the internal diameter of the front cover or via a sheet metal cover which is pressed onto the front cover external diameter, in an analogous manner to the spring cover in the hydraulic adjuster with the spiral spring. An additional adapter is installed between the flex pot and the camshaft, which additional adapter makes the feed and discharge of the control oil into/out of the pressure chambers A and B of the hydraulic adjuster possible by way of its inner channels and the ring channel on the external diameter. A supporting/plain bearing for the flex pot is formed between the adapter external diameter and the rotor internal diameter.
In this way, a particularly flat design of the camshaft adjusting system is possible. A separate output internal gear is dispensed with, as a result of which the system is less expensive and higher pressure intensity of the hydraulic adjuster can be realized in the same radial installation space. The cost ratio of the integration for the hardening of the locking slotted guide and the toothing system in a tempering treatment is improved. Furthermore, the outer shaft and the inner shaft can be adjusted with respect to the crankshaft independently of one another. The electric/hydraulic system therefore makes particularly high adjusting speeds of the inner camshaft possible even at low temperatures below 0° C.
It can therefore also be said that a decoupling of the adjusting ranges for the outer shaft and for the inner shaft is provided by way of the use of an internally toothed front cover of the hydraulic camshaft adjuster as an internal gear for the flex pot which is connected in a torque-proof manner to the inner shaft of the concentric camshaft.
In the following text, the embodiments described in greater detail with the aid of figures, in which different embodiments are shown and in which:
The figures are merely diagrammatic in nature and serve only for the comprehension of the embodiments. The same elements are provided with the same designations.
Features of the individual exemplary embodiments can also be realized in other exemplary embodiments. They can therefore be exchanged among one another.
The hydraulic camshaft adjuster 4 of the vane-cell type has, inter alia, a stator 6 which is closed in the axial direction by way of a ring-like front cover 7 on a side which faces away from the camshafts 2, 3. The front cover 7 has an internal toothing system 8, that is to say a toothing system which is configured on its internal diameter (see also
In the following text, the hydraulic camshaft adjuster 5 will be described in greater detail in relation to
The electric camshaft adjuster 5 has an electric motor 13 which has an output shaft 14. The latter is coupled in a torque-transmitting manner to the flex pot 9 via an Oldham coupling 15. The flex pot 9 is in turn attached to the inner, that is to say second camshaft 3, via an intermediate part 16 and a central screw 17. The Oldham coupling 15 can compensate for a radial offset of two parallel shafts. The flex pot 9 is mounted via an anti-friction bearing 18 on its internal diameter.
An (additional) adapter part 19 is arranged in the axial direction between the second camshaft 3 and the flex pot 9, which adapter part 19 has inner channels 20 and a ring channel 21 on the external diameter. These serve to feed and discharge the control oil into and out of the pressure chambers A and B of the hydraulic camshaft adjuster 4, which pressure chambers A and B are configured by way of the stator 6 and the rotor 11. A supporting or plain bearing 22 for the flex pot 9 is configured between the external diameter of the adapter part 19 and the internal diameter of the rotor 11.
The hydraulic camshaft adjuster 4 is closed in the axial direction on both sides by in each case one cover, a first cover which is arranged on the left in
The rotor 11 is mounted on the first camshaft 2 via a bearing point 25. In order to prevent an axial displacement away from the camshafts 2, 3, in particular of the construction which comprises the flex pot 9, a sheet metal cover 26 is provided in the first embodiment, which sheet metal cover 26 serves as a separate stop cover. For this purpose, the sheet metal cover 26 is mounted by a press fit onto the external diameter of the front cover 7.
As can be seen, in particular, in
In contrast to the first exemplary embodiment which is shown in
It can be seen from the detail view in
1 Camshaft adjusting system
2 First camshaft
3 Second camshaft
4 Hydraulic camshaft adjuster
5 Electric camshaft adjuster
6 Stator
7 Front cover
8 Internal toothing system
9 Flex pot
10 External toothing system
11 Rotor
12 Drive gear
13 Electric motor
14 Output shaft
15 Oldham coupling
16 Intermediate part
17 Central disk
18 Anti-friction bearing
19 Adapter part
20 Inner channel
21 Ring channel
22 Supporting/plain bearing
23 Cover
24 Rotor contact flange
25 Bearing point
26 Sheet metal cover
27 Screw
28 Opening
29 Ring
30 Chamfer
| Number | Date | Country | Kind |
|---|---|---|---|
| 102018123178.4 | Sep 2018 | DE | national |
