Patent Application
20090038570
The invention relates to a camshaft adjuster for an internal combustion engine according to the preamble of Claim 1.
Camshaft adjusters can be classified generally as follows:
A. Phase adjuster with an actuating element, that is, a functional unit that engages in the mass flow or energy flow, which is constructed, for example, hydraulically, electrically, or mechanically, and which rotates with drive elements of the camshaft adjuster.
B. Phase adjuster with a separate actuator, that is, a functional unit, in which the actuating parameter necessary for regulating the actuating element is formed from the regulator output parameter, and a separate actuating element. Here, there are the following constructions:
a. Phase adjuster with a co-rotating actuator and a co-rotating actuating element, for example, a high ratio gear drive, whose adjustment shaft can be advanced by a co-rotating hydraulic motor or centrifugal force motor and which can be retarded by a spring.
b. Phase adjuster with a co-rotating actuating element and a stationary, motor-fixed actuator, for example, an electric motor or an electric or mechanical brake, see also DE 100 38 354 A1, DE 102 06 034 A1, EP 1 043 482 B1.
c. Phase adjuster with a directionally dependent combination of the solutions according to a. and b., for example, a motor-fixed brake, in which a portion of the brake power is used, for example, for adjusting toward an advanced position, in order to tension a spring, which enables the retarding adjustment after the brake is deactivated, see also DE 102 24 446 A1, WO 03-098010, US 2003 0226534, DE 103 17 607 A1.
In systems according to B.a. to B.c., the actuator and actuating elements are connected to each other by an actuating shaft. The connection can have a configuration that is switchable or non-switchable, detachable or non-detachable, clearance-free or burdened with clearance, and flexible or stiff. Independent of the construction, the adjustment energy can be realized by the provision of a drive and/or brake power, as well as by use of loss powers of the shaft system (e.g., friction) and/or moments of inertia and/or centrifugal forces. Braking can also take place, advantageously in the “retarded” adjustment direction, under complete use or co-use of the friction power of the camshaft. A camshaft adjuster can be equipped with or without a mechanical limit of the adjustment range. As a gear drive in a camshaft adjuster, one-stage or multiple-stage triple-shaft gear drives and/or multiple linkage or coupling gear drives are used, for example, in constructions as wobble-plate gear drives, eccentric gear drives, planetary gear drives, undulating gear drives, cam plate gear drives, multiple linkage or coupling gear drives or combinations of the individual constructions for a multiple-stage configuration.
While conventional, hydraulically actuated camshaft adjusters or camshaft adjusters in configurations with vane cells, pivot vanes, or segment vanes have the advantage that
From DE 37 37 602 A1, it is known to use a differential gear drive as a variable ratio gear drive, in which drive is realized by means of a drive wheel in drive connection with the crankshaft and a driven part to the camshaft aligned with the longitudinal axis, while the feeding of the drive movement of the electrical actuating assembly is realized radial to the previously mentioned longitudinal axis.
From DE 102 60 546 A1, a hydraulic camshaft adjuster is known, to which a vacuum pump can be coupled on the side facing away from the camshaft aligned with the longitudinal axis.
DE 38 30 382 C1 discloses the drive of a planetary gear drive mounted axially before a variable ratio gear drive using an electrical actuating assembly, whose longitudinal axis is offset parallel to the longitudinal axis of the camshaft and the variable ratio gear drive.
The variable ratio gear drive known from U.S. Pat. No. 4,747,375 is constructed as a planetary gear drive, in which, for a first construction, the ring gear is driven by a servomotor, whose longitudinal axis is arranged parallel to the longitudinal axis of the camshaft, while the sun wheel of the planetary gear drive is in drive connection with the crankshaft of the internal combustion engine and the planetary gear drive is driven relative to the camshaft by a connecting piece. For an alternative construction, the drive is realized using the servomotor and the sun wheel for an aligned orientation of the servomotor relative to the longitudinal axis of the camshaft, while the crankshaft drives the ring gear by driving the connecting piece of the planetary gear drive.
Finally, DE 103 52 255 A1 discloses a coupling of an electrical actuating assembly via a flexible shaft, a pneumatic motor, a hydromotor, so that the actuating assembly can be arranged at any point. Furthermore, from the publication the proposal is to be taken to arrange an electrical actuating assembly parallel to the camshaft and to arrange a gear stage between the variable ratio gear drive and the electrical actuating assembly.
The present invention is based on the objective of providing a camshaft adjuster, which offers expanded possibilities for integration of the same in an internal combustion engine. In particular, the invention is based on the objective of allowing a drive of an additional assembly via the camshaft adjuster.
According to the invention, this objective is met by the features of the independent Claim 1. Additional constructions of the invention emerge accordingly from the features of the dependent Claims 2 to 10.
According to the invention, the feeding of the drive movement of the actuating assembly into the variable ratio gear drive does not take place on the “free end” of the variable ratio gear drive, that is, on the side facing away from the camshaft, but instead on the side facing the camshaft. Here, the invention has recognized that an installation space typically provided on the side of the camshaft adjuster facing the camshaft for hydraulically actuated camshaft adjusters is not used for camshaft adjusters with an electrical actuating assembly and variable ratio gear drive. Thus, this installation space can be used according to the invention. This can be the case, on one hand, when the same internal combustion engine is to be used, on one side, with a hydraulic camshaft adjuster and, on the other side, in a variant with a camshaft adjuster with an actuating assembly and a variable ratio gear drive. On the other hand, such a construction is also possible for a total construction series of internal combustion engines with actuating assemblies. Here, only the shaft feeding the power to the variable ratio gear drive can be arranged on the side of the variable ratio gear drive facing the camshaft or also the entire actuating assembly with an allocated actuating shaft. The free installation space for hydraulic systems is produced, in particular, due to the elimination of transmission elements for a hydraulic medium and associated actuating valves.
Due to the elimination of the feeding of the drive movement on the side of the variable ratio gear drive facing away from the camshaft, free installation space is produced on this side, which can be used for this purpose according to another construction of the invention, such that, on this side, a shaft is guided out, by which an additional assembly, in particular, a vacuum pump, a fuel-injection pump, or an ignition distributor, can be driven. In this way, the shaft can be arranged aligned or parallel to the longitudinal axis of the camshaft and the camshaft adjuster. The shaft guided out of the variable ratio gear drive on the side facing away from the camshaft can be coupled, in terms of driving, with any of the three gear drive elements of the variable ratio gear drive, in particular, with a sun, a connecting piece, or a ring gear for the case that the variable ratio gear drive is constructed as a planet set.
Through the construction according to the invention, deviating from a connection of a camshaft, a variable ratio gear drive, and an electrical actuating assembly one after the other in the previously mentioned sequence, axial installation space can be saved, wherein the savings can equal up to the axial installation length of the actuating assembly including an allocated actuating shaft. Furthermore, for the previously mentioned connection of camshaft, variable ratio gear drive, and actuating assembly one after the other, the support of the actuating assembly—next to an already present wall of the cylinder head, in the region of which the camshaft is supported and/or hydraulic medium for a hydraulic camshaft adjuster is guided—an additional cylinder head-fixed support wall or a corresponding carrier is required, which, nevertheless has guaranteed the accessibility of the drive wheel of the camshaft adjuster for the traction element of the actuating drive, e.g., by a suitable opening. Such an additional wall can be spared according to the invention, so that the camshaft adjuster can be arranged freely accessibly on the outer side of the cylinder head.
The actuating assembly can have an arbitrary construction, for example, as an electric drive assembly or as a hydromotor, and it can act as a drive unit and/or as a brake.
Corresponding to another aspect of the invention, the actuating assembly is integrated into an end face of the cylinder head, by which an especially compact construction is produced for a simultaneously good support of the actuating assembly.
Advantageously, the actuating assembly is arranged adjacent to a first camshaft bearing, where installation space not used from prior applications with hydraulic camshaft adjusters can be utilized.
An especially compact construction of the invention is produced when the camshaft is guided through the actuating assembly. In this way, free installation space present radially in the surroundings of the camshaft can be used for the actuating assembly. Advantageously, components, in particular, an actuating shaft and an allocated rotor of the actuating assembly are constructed as hollow bodies or hollow shafts, through which the camshaft or connection elements between the camshaft and the gear element allocated to the camshaft are guided.
According to another feature of the invention, components of the actuating assembly, in particular, the previously mentioned actuating shaft and a rotor of an actuating assembly allocated to this actuating shaft are supported relative to the camshaft. For example, a roller bearing can be supported on the inside in the radial direction on an inner peripheral surface of the rotor or actuating shaft. Under some circumstances, the entire camshaft adjuster is supported by such a bearing and only one stator of the actuating assembly is supported with its housing, for example, on a cylinder head. A bearing of the rotor and actuating shaft of the actuating assembly on the camshaft has the result that no relative movement is generated in the bearing, as long as the camshaft adjuster is not adjusted. This is advantageous in terms of the thermal and mechanical loading of the bearing.
For another construction of the camshaft adjuster according to the invention, both the rotor of the actuating assembly and also the stator of the actuating assembly are supported by an end cylinder head wall. This can lead to the result that the actuating assembly can be completely sealed, so that no lubricant can enter into the actuating assembly from the internal combustion engine. In this case, permanent lubrication of the bearing provided in the actuating assembly can be used. Furthermore, the rotor can be supported by a roller bearing against the stator, which is supported, in turn, on the end cylinder head wall. Such a construction has the advantage that bearing inaccuracies or production tolerances, for example, between the cylinder head and camshaft or other components, cannot negatively affect the function of the actuating assembly. On the other hand, in such a case, the use of bearings with an enlarged diameter can be necessary, by which the number of roller bodies and the mass of the rotating parts can increase and an enlarged friction radius of the bearing is produced.
As an advantageous coupling of the actuating assembly and the allocated gear element, a polygonal-shaft-hub connection is produced, for example, a polygon P4C or polygon P3G shaft hub connection, which can be constructed, in particular, according to the standards DIN 32711 and DIN 32712 and the corresponding constructions and modifications available on the market. Such connections can lead to the following advantages:
easy assembly and disassembly,
low stress peaks due to a rounded convex profile shape,
high load carrying capacities relative to other positive-fit shaft-hub connections,
accurate-fit production of also hardened connection partners through grinding,
self-centering and torsion load for a P3G profile,
equal thickness character for P3G profile and
good axial displacement under torsion load for a P4C profile,
longitudinal displacement of the P4C profile under torque moment,
grindability of the hub profile P3G.
Alternatively or additionally, vulcanization of a compensation element between the actuating shaft, actuating element, gear element, and actuating assembly is also possible.
Also possible is the use of a magnet coupling with or without an air gap, for which the motor also can have a closed construction and which can allow sliding in the region of the magnet coupling.
Corresponding to a refinement of the camshaft adjuster according to the invention, a longitudinal axis of the actuating assembly, in particular, the longitudinal axis of the drive shaft of the actuating assembly, can be oriented parallel to the camshaft. In this way, the installation space required for the actuating assembly can be mounted even farther away from the camshaft. It is also possible to connect a gear stage, for example, a spur wheel stage, by which the rotational speed ratios and the moments generated in the actuating assembly can be suitably converted, between the actuating assembly and the gear element of the variable ratio gear drive.
Advantageous improvements of the invention emerge from the patent claims, the description, and the drawings. The advantages of features and combinations of several features named in the introduction of the description are merely examples, and these do not necessarily have to be the goal of embodiments according to the invention. Additional features are to be taken from the drawings—in particular, the illustrated geometries and the relative dimensions of several components relative to each other and also their relative arrangement and active connection. The combination of features of different embodiments of the invention or of features of different claims is also possible deviating from the selected associations of claims and is herewith suggested. This also relates to features, which are shown in separate drawings or named in the description of these drawings. These features can also be combined with features of different claims. Likewise, features listed in the claims can be left out of other embodiments of the invention.
Additional features of the invention emerge from the following description and the associated drawings, in which embodiments of the invention are shown schematically. Shown are:
In the figures, components that correspond in terms of their shape and/or function are provided generally with the same reference symbols.
The actuating shaft 4 is driven by an electrical actuating assembly 7 or is in active connection with a brake. The electrical actuating assembly 7 is supported relative to the surroundings, for example, the cylinder head 8 or another motor-fixed part.
For the embodiment shown in
the contact surfaces between drive conical wheel 20 and wobble plate 15,
the contact surface between wobble plate 15 and driven conical wheel 18,
the bearing 19,
bearing element 14, and/or
bearing element 17.
For this purpose, lubricant is supplied and/or forwarded in a continuous, cyclic, pulsating, or intermittent way via lubricant channels. Via a supply recess 25 of the cylinder head 8, the lubricant is fed to a flow channel 26 of the camshaft 6, which communicates with a flow channel 27, which has a hollow cylinder shape between an inner peripheral surface 28 of the hollow shaft 16 and an outer peripheral surface 29 of the central screw 22. Through the use of radial boreholes 30 of the hollow shaft 16, the lubricant can be discharged out of the flow channel 27 outward in the radial direction and fed to the lubricating positions.
The variable ratio gear drive 2 shown in
a sun wheel,
planets mounted on a connecting piece, and also
a ring gear.
For example,
the actuating assembly 7 is connected via the actuating shaft 4 to the connecting piece,
the ring gear is connected to the drive wheel 3,
and the sun wheel is connected to the camshaft 6.
In an alternative construction, the gear elements carrying out the conversion involve, for example, an axial moving actuating element, which is acted upon by the actuating assembly and which interacts with a drive wheel-fixed threading and a camshaft-fixed threading, cf., e.g., EP 1 403 470 A1.
For the embodiment of the invention shown in
For the embodiment shown in
For the shown support of the rotor 37 of the actuating assembly 7 on the camshaft 6, no relative movement occurs between the actuating shaft 4 and the camshaft 6, as long as there is no adjustment of the camshaft adjuster 1. This is advantageous in terms of energy, because no electrical energy must be applied for compensating the friction in the bearing 34, without adjustment taking place.
To form the assembly as simple as possible, advantageously the variable ratio gear drive 2 and the electrical actuating assembly 7 are constructed as a complete unit. This can be realized, for example, by a prolonged hollow cylinder-shaped actuating shaft 4, on which, in an end region, the rotor 37 is attached and which extends into the variable ratio gear drive 2. Furthermore, deviating from the embodiment shown in
Deviating from the previously described embodiment according to
For a drive-fixed connection of components of the camshaft adjuster 1 according to the invention, for example, a drive connection between the rotor 37 and actuating shaft 4 and/or a coupling of the actuating shaft 4 with the allocated gear element of the variable ratio gear drive 2, advantageously radially small connection elements are to be selected. Possibilities here are, for example, a shaft-hub connection of the polygonal P4C type or polygon P3G type. Also conceivable is vulcanization of an elastic compensation element into the previously mentioned coupling regions. Alternatively or additionally, a magnetic coupling with or without an air gap can be used for a coupling. Here, a closed construction of the motor can be possible. Sliding of the magnetic coupling can be advantageous for one construction of an overload protection device. Under some circumstances, magnetization of the surrounding components and an increase in the costs and the inertia of masses is added, as well as the fact that metal particles can be attracted by such magnetization.
For solutions according to the invention, the actuating assemblies 7 are formed with a hollow driven shaft or actuating shaft 4, so that the camshaft 6 can be guided through the actuating assembly 7. The seal of the actuating shaft 4 relative to the surroundings in the cylinder head 8 or a shaft passing through the housing of the variable ratio gear drive 2 is of special importance for such a construction of the actuating assembly 7. For such seals, e.g., corresponding to the seals 44, 45, the following constructions can be possible:
The penetration of lubricant into the actuating assembly can be disadvantageous if iron particles are located in the lubricant, for example, due to abraded parts. These are attracted by a magnetic field of the actuating assembly 7 and thus, over the course of time, can increase an existing air gap or weaken a magnetic field.
While the actuating shaft 4, which is coupled directly with a gear element of the variable ratio gear drive 2, is constructed as a driven shaft of the actuating assembly 7 or is coupled with this assembly in a rotationally locked way or via a suitable coupling for the embodiments according to
For the embodiment shown in
For the embodiment shown in
According to the embodiment shown in
For the embodiment shown in
It is further proposed to construct the actuating assembly 7, the variable ratio gear drive 2, and the actuating shaft 4 in an interconnected way and/or to join the functional units of both components with each other:
For example, according to the embodiment shown in
It is also possible, as shown in
The electrical actuating assembly 7 can be formed as a drive unit or as a brake. In addition to the use of an electrical actuating assembly, an arbitrary actuating assembly, for example, a hydromotor, can be used, which acts as a drive assembly and/or as a brake assembly.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102006007584.6 | Feb 2006 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP07/50520 | 1/19/2007 | WO | 00 | 8/12/2008 |
