Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Reexamination Certificate
1999-12-27
2001-02-27
Lo, Weilun (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
C123S090310
Reexamination Certificate
active
06192844
ABSTRACT:
DESCRIPTION
1. Field of the Invention
The invention relates to a device for varying the control times of gas-exchange valves of an internal combustion engine according to the features of claim
1
which form the preamble, and it can be implemented with particular advantage in camshaft adjusting devices with an impeller.
2. Background of the Invention
Such a device is previously known in a generically determined fashion from DE-A 196 23 818. This device comprises, on the one hand, a drive wheel which is constructed as an outer rotor and is connected in driving terms to a crankshaft of the internal combustion engine via a drive chain and has a cavity formed by a hollow cylindrical peripheral wall and two side walls and is constructed on one of its side walls with a tooth system for the drive chain. On the other hand, the device comprises an impeller which is constructed as an inner rotor, is connected in a rotationally fixed fashion to the camshaft of the internal combustion engine, is inserted into the cavity of the drive wheel, and has two or more radially arranged blades on the peripheral surface of its wheel hub. Moreover, extending from the inner lateral surface of the peripheral wall of the drive wheel into the cavity of the drive wheel are at least two or more radial bounding walls which are directed toward the longitudinal center axis of the drive wheel and are operationally connected to the wheel hub of the impeller, so that two or more hydraulic operating chambers are formed inside the device by the lateral surfaces of the bounding walls and by the inner lateral surface of the peripheral wall of the drive wheel together with the peripheral surface of the wheel hub of the impeller. In this case, each operating chamber of the device is subdivided in turn into in each case two hydraulic pressure chambers acting against one another by in each case one blade of the impeller extending into this operating chamber, which pressure chambers, given an optional or simultaneous application of pressure by a hydraulic pressure fluid within a maximum pivoting angle, effect a pivoting movement or fixing of the impeller with respect to the drive wheel, and thus of the camshaft with respect to the crankshaft.
In addition, the device in accordance with DE-A 196 23 818 is constructed in such a way that in the absence of the application of pressure by in each case one pressure chamber of the device, the impeller and a drive wheel can be intercoupled by a locking element in a preferred mutual position, which is constructed in the particular case as a so-called axial pin and is arranged together with a compression spring in an axial bore in the impeller. This axial pin can be displaced by the force of the compression spring into a coupling position in a locking bore which is recessed into the opposite inner side of a side wall of the drive wheel and is connected hydraulically to one of the pressure chambers of the device in such a way that upon application of pressure by this pressure chamber the axial pin moves again by the hydraulic pressure fluid into its decoupling position in the axial bore in the impeller.
It is disadvantageous in this known device that the maximum pivoting angle, limited by the lateral surfaces of the bounding walls in the drive wheel, of the impeller is fixed with respect to the drive wheel in accordance in each case with the engine-specific conditions of a specific design of an internal combustion engine by a specific number and size of the bounding walls and of the blades of the device, and can no longer be varied. Since the respective engine-specific conditions on each internal combustion engine thereby set bounds to the maximum pivoting angle of such devices, and also require different maximum pivoting angles of the devices in the case of different designs of internal combustion engines, the use of a device with a uniform pivoting angle for a plurality of designs of internal combustion engines is not possible, and the device needs to be adapted in a complicated way for each individual design of an internal combustion engine. However, in the production of such devices for different designs of internal combustion engines, this impairs the use of identical parts, and therefore necessitates a cost-intensive production of a multiplicity of similar components for the purpose of implementing different maximum pivoting angles. If, in this case, these components are produced, for example, by sintering, the increased production costs of such devices are further influenced negatively by virtue of the fact that separate sintering tools are required for each device having a different maximum pivoting angle.
OBJECT OF THE INVENTION
It is therefore the object of the invention to design a device for varying the control times of gas-exchange valves of an internal combustion engine, in particular camshaft adjusting devices with an impeller which, owing to the possibility of simple adaptation of the maximum pivoting angle of the impeller with respect to the drive wheel using as many identical parts as possible to produce it on different designs of internal combustion engines.
SUMMARY OF THE INVENTION
According to the invention, this object is achieved in such a way that the device has between the impeller and the drive wheel an additional angle-limiting device with the aid of which the maximum pivoting angle of the impeller, which is limited per se by the lateral surfaces of the bounding walls in the drive wheel, can be reduced with respect to the drive wheel to a smaller pivoting angle. In this case, a virtually stepless reduction in the pivoting angle is possible merely by exchanging a component of the device or an element of this angle-limiting device for another component, which likewise reduces the pivoting angle, of the device or an element of the angle-limiting device, and the device can be used while retaining all the remaining components on all designs of internal combustion engines for which the possible relative angle of rotation between their camshaft and their crankshaft is smaller than or equal to the maximum pivoting angle, limited by the lateral surfaces of the bounding walls in the drive wheel, of the impeller with respect to the drive wheel.
In an expedient development of the device according to the invention, the additional angle-limiting device on the one hand comprises an angle-limiting groove in the shape of an annular segment recessed into the inner side of a side wall of the drive wheel and whose radius origin is arranged on the longitudinal center axis of the device and on the other hand comprises a stop bolt which is arranged on the axial end of the impeller, which is situated opposite this side wall, and projects into the angle-limiting groove in the side wall of the drive wheel. In this case, the groove ends of the angle-limiting groove are constructed as angle-limiting stops against which the stop bolt is arranged to bear in the maximum pivoting positions of the impeller with respect to the drive wheel.
The devices are additionally constructed in a way known per se such that in the absence of the application of pressure by in each case one pressure chamber of the device, the impeller and the drive wheel can be intercoupled by a locking element in at least one preferred mutual position, the locking element being constructed as an axial pin which is arranged, together with the compression spring in an axial bore in the impeller and can be displaced by the spring force into a coupling position in a locking bore in the opposite inner side of a side wall of the drive wheel. In this case, the locking bore in the side wall of the drive wheel is connected hydraulically to a pressure chamber of the device in such a way that upon application of pressure by this pressure chamber the axial pin can be moved again by the hydraulic pressure fluid into a decoupling position in the axial bore in the impeller.
In a first preferred embodiment of the device according to the invention, the stop bolt of the angle-limiting device is therefore fastened inside an axial blind bo
Scheidt Martin
Strauss Andreas
Bierman, Muserlian and Lucas
Ina Walzlager Schaeffler OHG
Lo Weilun
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