Internal-combustion engines – Poppet valve operating mechanism – Hydraulic system
Patent
1991-05-28
1992-05-19
Cross, E. Rollins
Internal-combustion engines
Poppet valve operating mechanism
Hydraulic system
123 9016, 123 9048, F01L 902, F01L 112
Patent
active
051138115
DESCRIPTION:
BRIEF SUMMARY
STATE OF TECHNOLOGY
The invention is based on a hydraulic valve control device for internal combustion engines. In principle, such an electrohydraulic control device must satisfy several requirements. There is, on the one hand, very little free space available in the vicinity of the cylinder head of an internal combustion engine, therefore all components located there should have as small as possible dimensions. On the other hand, this is an area which is subject to becoming relatively hot, a factor which needs to be remembered when designing and configuring components, in particular moving parts. It is of decisive importance for the quality of the control that the oil which is moved to and fro should be as small as possible, since the oil which is shunted to and fro has an effect, due to cross-section control, on the quality of the precision of the control or the compressibility of the controlling oil, which is of course of particular disadvantage in larger oil volumes. It is a different matter with parts which can present a source of faults, such as for example the magnetic valves, the number of which should be kept as low as possible, aiming to control several engine valve units, if possible, via just one solenoid.
In a known hydraulic valve control device of the generic type (DE-OS 35 11 820), a slide valve is controlled via a solenoid, this slide valve in turn controls the linkage between pressure chamber and reservoir. The solenoid is arranged close to the slide valve, because due to the design, the solenoid magnet is relatively distant from the engine valve. This leads to relatively long pipe runs, and an appropriately large volume of hydraulic oil between the reservoir and the pressure chamber.
ADVANTAGES OF THE INVENTION
The hydraulic valve control device has the advantage that the space provided in the pressure chamber for the cam piston spring, and hence detrimental space, is used as a reservoir, so that the dimensions of the valve control device do not have to be increased due to the integration of the reservoir piston, and that the hydraulic lines between the individual control areas within the valve control unit are minimised. Extra space for the reservoir in the area of the cylinder head is therefore no longer required. The control of the pressure channel between the pressure chamber and the reservoir area can be implemented in different ways, the important point being that this control is directly or indirectly implemented hydraulically. The hydraulic feed must be radial, since the cam piston is axially displaced in operation and requires a radial guide which can here be used for the feed of the control hydraulics by virtue of the fact that the guide can be bridged via an appropriate groove system in the surface area and the bore. A further advantage exists in the savings made during component manufacture. Since the cam piston and the reservoir piston are machined components running in precision bores, it is therefore sufficient to provide only one related precision bore in the cylinder head, as the other bore in the cam piston is machined on an automatic lathe.
One refinement of the invention consists of a solenoid which is triggered via an electronic control unit which processes engine parameters, for the control of the pressure line. Such a solenoid enables the high frequencies required for the control to be achieved without difficulty. Above all, it is possible to process via an electronic control unit all parameters conceivable and of interest, for the control of the engine valves. In principle, however, it is conceivable that the pressure line can be controlled via mechanical or hydromechanical means, with the reservoir piston as the core of the invention being arranged in the cam piston, which is designed as a tubular piston.
In accordance with a further advantageous refinement of the invention, the reservoir piston, as a moving part of the control valve, controls the connection between the pressure line and the reservoir, in which process a control line for hydraulic oil, fed un
REFERENCES:
patent: 4164917 (1979-08-01), Glasson
patent: 4218995 (1980-08-01), Aoyama
patent: 4452186 (1984-06-01), List et al.
patent: 4671221 (1987-06-01), Geringer et al.
Linder Ernst
Rembold Helmut
Cross E. Rollins
Greigg Edwin E.
Greigg Ronald E.
Lo Weilun
Robert & Bosch GmbH
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