Internal-combustion engines – Four-cycle – Variable clearance
Reexamination Certificate
2000-09-06
2001-08-21
McMahon, Marguerite (Department: 3747)
Internal-combustion engines
Four-cycle
Variable clearance
Reexamination Certificate
active
06276314
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a drive for positioning a setting (adjusting) device in a piston-type internal-combustion engine.
In certain modes of application it may be a requirement, for example, to shift the position of a first shaft in such a manner that the shaft axis is displaced perpendicularly to itself with respect to a fixed reference plane while the rotary axis of a second shaft which extends parallel to the first shaft, preserves its defined position relative to the reference plane. Such a requirement is encountered, for example, in an internal-combustion engine in which a change of volume of the combustion chamber has to be effected by shifting the crankshaft axis toward or away from a reference plane. For such a change of position of the crankshaft significant setting and holding forces are necessary which may be applied only with difficulty by conventional electric actuators which, in an internal-combustion engine of a vehicle, have to be supplied with electric energy from an onboard power source.
Shifting devices of the above-outlined type may also be required for adjusting the cam shaft in an internal-combustion engine.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an improved drive of the above-outlined type which may apply large setting and holding forces with little energy input for positioning a setting device of an internal-combustion engine.
This object and others to become apparent as the specification progresses, are accomplished by the invention, according to which, briefly stated, a setting assembly in a piston-type internal-combustion engine includes a setting device connected to a component for adjusting the position of the component; a power device; and a gearing having an input member connected to the power device for driving the gearing by the power device, an output member connected to the setting device for driving the setting device by the gearing; a down-stepping arrangement forming part of the gearing for providing a substantially down-stepped transmission ratio between the input and output members of the gearing; and a reversing arrangement for reversing the direction of motion of the output member.
By using a highly down-stepped gearing, large setting forces may be applied with a small driving force. According to a further advantageous feature of the invention, the gearing may be selectively immobilized (locked) or released in any given setting position by a switchable locking arrangement which requires only small holding forces.
In accordance with another advantageous feature of the invention, the gearing is self-locking. This may be accomplished by a gearing which is a worm-and-gear drive and in which the worm is on the driving side.
The back-and-forth motion required for the positioning of the setting device between two end positions is effected expediently by a rotary drive. In case of an electric rotary drive the back-and-forth motion may be produced electrically by a reversal of the rotary direction. It is, however, particularly expedient if the drive means is constituted by the internal-combustion engine itself, in which case the engine is connected with the gearing of the setting device by a switchable clutch. According to the invention in such a drive arrangement the means for reversing the rotary direction is formed by a switchable reversing gear unit of the gearing. The driving force may be taken from the crankshaft of the internal-combustion engine via a drive belt, preferably the toothed belt for actuating the cam shaft or from the belt which drives the alternator. Since the drive operates with a constant rotary direction, the required back-and-forth motion for the setting device may be effected by a switchable reversing gear unit of the gearing.
According to an advantageous feature of the invention, the switchable clutch is constituted by an electromagnetic clutch which operates without mechanical contacting. Such an electromagnetic clutch has the advantage that the setting process may be performed smoothly. Thus, particularly in case of small setting displacements, the setting process may be performed slowly and continuously or in a timed manner dependent on the actuation of the clutch. The electric energy required for actuating the electromagnetic clutch is significantly less than in case of a direct drive from an own setting motor.
As a particularly advantageous mode of application, the invention provides that the setting device is utilized for shifting the engine crankshaft to change the volume of the combustion chamber in the engine cylinders.
REFERENCES:
patent: 4152955 (1979-05-01), McWhorter
patent: 4485768 (1984-12-01), Heniges
patent: 4535730 (1985-08-01), Allen
patent: 5680840 (1997-10-01), Mandella
patent: 5732673 (1998-03-01), Mandella
FEV Motorentechnik GmbH
Kelemen Gabor J.
McMahon Marguerite
Venable
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