Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Reexamination Certificate
2000-08-01
2001-09-04
Lo, Weilun (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
Reexamination Certificate
active
06283075
ABSTRACT:
FIELD OF THE INVENTION
The invention concerns a locking device for a device for varying valve timing of gas exchange valves of an internal combustion engine, particularly for a vane-type adjusting device, said locking device comprising a drive pinion configured as an outer rotor and connected in driving relationship to a crankshaft of the internal combustion engine by a traction means, said drive pinion having a hollow space defined by a circumferential wall and two side walls, and a winged wheel inserted into this hollow space and configured as an inner rotor which is connected rotationally fast to a camshaft of the internal combustion engine, said winged wheel comprising on the periphery of its wheel hub at least one wing that is arranged in an axial groove and extends radially away from the wheel hub, at least one working chamber being defined within the hollow space of the drive pinion by intermediate walls that start from the inner surface of the circumferential wall of the drive pinion and extend toward the central longitudinal axis of the device, said working chamber being divided by a wing of the winged wheel extending in each working chamber into two hydraulic pressure chambers which, by an optional successive or simultaneous pressurizing by a hydraulic pressure medium, effect a turning and/or fixing of the winged wheel relative to the drive pinion, while in the absence of pressure loading of one of the pressure chambers, the winged wheel and the drive pinion can be coupled to each other mechanically in at least one preferred position.
BACKGROUND OF THE INVENTION
A generic device of the pre-cited type is known from U.S. Pat. No. 4,858,572. In a preferred embodiment of this device, six equally large working chambers are formed in the hollow space of the drive pinion between six circumferentially opposed intermediate walls. These six working chambers are divided into fluid-tight first and second pressure chambers by six wings rigidly connected to the hub of a winged wheel which is connected to the camshaft. The mechanical coupling between the winged wheel and the drive pinion of the device is accomplished by a spring-loaded locking pin arranged in a radial bore of one of the intermediate walls. This locking pin engages a reception bore arranged between two wings in the hub when the wings of the winged wheel abut in an end position against the intermediate walls of the drive pinion and the first pressure chambers of the device are cut off from the pressurization by the hydraulic pressure medium. When, upon a renewed pressurization of these pressure chambers, the hydraulic medium pressure exceeds a set value, the locking pin is displaced against the force of its spring entirely out of the reception bore in the hub into the radial bore in the intermediate wall so that the mechanical coupling between the winged wheel and the drive pinion is released. When, after a relative rotation between the winged wheel and the drive pinion, the wings are brought into abutment in their opposite end position against the intermediate walls of the drive pinion, and the second pressure chambers of the device are cut off from the pressurization by the hydraulic pressure medium, a second mechanical coupling between the winged wheel and the drive pinion is effected by a locking pin similarly arranged in another intermediate wall. This locking action is likewise undone when a defined pressure medium pressure in the second pressure chambers is exceeded.
A mechanical coupling of this type between the winged wheel and the drive pinion, however, has the drawback that it is formed by a plurality of additional separate components which in view of the extra expenses for their fabrication and assembly disadvantageously increase the manufacturing costs of such a vane-type adjusting device. Also, due to the configuration of the locking pins as simple pressure pins, there exists the possible drawback that the locking pins be deformed when they have been subject to high stresses acting in both directions of rotation so that a continued, satisfactory locking of the device is then not always guaranteed.
OBJECT OF THE INVENTION
The object of the invention is therefore to conceive a locking device for a device for varying the valve timing of gas exchange valves of an internal combustion engine, particularly for a vane-type adjusting device, which locking device should comprise the smallest possible number of separate components so that its manufacturing and assembly costs are low, and said locking device must guarantee a continued, satisfactory locking of the adjusting device even after taking up high stresses in both directions of rotation.
SUMMARY OF THE INVENTION
In accordance with the invention, this object is achieved with a device for varying valve timing of gas exchanqe valves of an internal combustion engine, particularly for a vane-type adjusting device, said locking device comprising a drive pinion (
3
) configured as an outer rotor and connected in driving relationship to a crankshaft of the internal combustion engine by a traction means, said drive pinion having a hollow space (
8
) defined by a circumferential wall (
4
) and two side walls (
6
,
7
), and a winged wheel (
9
) inserted into this hollow space (
8
) and configured as an inner rotor which is connected rotationally fast to a camshaft (
2
) of the internal combustion engine, said winged wheel (
9
) comprising on the periphery (
10
) of its wheel hub (
11
) at least one wing (
13
) that is arranged in an axial groove (
12
) and extends radially away from the wheel hub (
11
), at least one working chamber (
20
) being defined within the hollow space (
8
) of the drive pinion (
3
) by intermediate walls (
16
) that start from the inner surface (
5
) of the circumferential wall (
4
) of the drive pinion (
3
) and extend toward the central longitudinal axis of the device (
1
), said working chamber (
20
) being divided by a wing (
13
) of the winged wheel (
9
) extending in each working chamber (
20
) into two hydraulic pressure chambers (
21
,
22
) which, by an optional successive or simultaneous pressurizing by a hydraulic pressure medium, effect a tuning and/or fixing of the winged wheel (
9
) relative to the drive pinion (
3
), while in the absence of pressure loading of one of the pressure chambers (
21
or
22
), the winged wheel (
9
) and the drive pinion (
3
) can be coupled to each other mechanically in at least one preferred position. By the fact that the mechanical coupling between the winged wheel and the drive pinion of the device can be established by at least one wing of the winged wheel, which wing is configured both as a pivoting element of the winged wheel and as a locking element which can be arrested in a locking position on the drive pinion by an auxiliary energy when a pressure of the hydraulic pressure medium falls short of a pressure required for pivoting the winged wheel, and which can be arrested in a releasing/pivoting position within its associated working chamber when a defined value of hydraulic pressure medium pressure is exceeded.
According to a further advantageous feature of the invention, each wing of the winged wheel configured as a locking element is arranged for radial movement within its axial groove in the wheel hub of the winged wheel, and a free end of said wing is in positive engagement with a corresponding axial fixing groove in the inner surface of the circumferential wall of the drive pinion in one or more locking positions of the device. Each axial fixing groove preferably extends over the entire width of the inner surface of the circumferential wall of the drive pinion, and a width of the axial fixing groove is such that the wing concerned can slip easily into said axial fixing groove while, at the same time, a rattling of the wing in its locking position is prevented.
It has proved to be particularly economic to configure only one wing of the winged wheel as a locking element irrespective of the number of wings present. This one wing is then in locking connection only in one of its end positio
Dietz Joachim
Schafer Jens
Strauss Andreas
Bierman, Muserlian and Lucas
Ina Walzlager Schaeffler OHG
Lo Weilun
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