Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Patent
1994-10-18
1996-10-22
Lo, Weilun
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
123 9031, F01L 1344
Patent
active
055666515
DESCRIPTION:
BRIEF SUMMARY
STATE OF THE ART
It is known to use such a device in internal combustion engines with which valve timings can be adapted to engine operation to obtain an optimum operation of the engine in the largest possible speed range. By this, improvements with regard to torque, performance, exhaust gas emission, idling behavior and fuel consumption can be obtained.
A valve control for inlet valves is known from the species defining document, EP-OS 03 35 083, in which the inlet camshaft can be adjusted with the help of a phase transformer. An adjusting element is mounted for axial displacement and comprises an exclusively hydraulically actuatable piston which is associated with two working chambers and controlled by an adjusting piston of a directional control valve. This adjusting piston is displaced between two discrete end positions by a solenoid switch which is arranged on the longitudinal axis of the camshaft and therefore increases the axial design space requirement of the engine. This construction, and particularly the control valve, permits only a two-point adjustment of the inlet camshaft. The extra design space required due to the chosen arrangement of the solenoid is disadvantageous particularly when the engine is installed crosswise which is general current practice in passenger cars with front wheel drive.
EP-OS 01 12 494 describes another camshaft adjusting device which comprises a hydraulically actuatable piston. The device has a circular ring-shaped configuration and is provided with an internal and an external gearing, one of these gearings being a helical gearing. An axial displacement of the piston due to application of a pressure medium effects a phase shift between the components connected to the piston by the gearings, i.e. a camshaft drive pinion and a component connected indirectly to the camshaft. Disadvantageously, this solution requires a pressure medium supply through the mounting of the camshaft and a bore extending axially in the camshaft. Pressure medium is discharged from the adjusting device at an axial end thereof through a housing of the adjusting device. This advantageously necessitates a modification of the camshaft. A further disadvantage is the larger overall axial length of the engine.
An adjusting device described in DE-A 39 29 621 comprises a shaft member which is flange-mounted on an end of a camshaft, the adjusting device being integrated in this shaft member which forms an extension of the camshaft. Pressure medium supply is effected through bores extending radially upto the shaft member in a mounting region. Due to the configuration of this device, there results an adjusting piston with relatively small piston areas so that the adjusting forces of the device dependent thereon are likewise small. Moreover, the radial design space requirement of this adjusting device is relatively large due to the fact that the adjusting element and the pressure medium supply are arranged in one and the same housing.
OBJECTS OF THE INVENTION
The object of the invention is to provide an adjusting device which is separate from the camshaft mounting, which does not have an adverse effect on the strength of the camshaft and in which the pressure medium supply is substantially separate from the adjusting element for assuring an optimized application of pressure chambers, with, at the same time, a limited radial design space requirement.
This and other objects and advantages of the invention will become obvious from the following detailed description.
THE INVENTION
A device for continuous angular adjustments between at least two shafts in driving relationship, particularly a crankshaft and a camshaft of an internal combustion engine, comprising an adjusting element (4) which is connected to a shaft to be adjusted while being arranged in an axial direction thereto and comprising a hydraulically actuatable piston (14) which is connected to a pressure medium circuit, characterized in that an end region of the shaft to be adjusted, which can be a camshaft (5) or an intermediate shaft, is surrou
REFERENCES:
patent: 5012773 (1991-05-01), Akasaka et al.
patent: 5144921 (1992-09-01), Clos et al.
patent: 5189999 (1993-03-01), Thoma
patent: 5301639 (1994-04-01), Satou
Golovatai-Schmidt Eduard
Strauss Andreas
INA Walzlager Schaeffler KG
Lo Weilun
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