Internal-combustion engines – Poppet valve operating mechanism – Hydraulic system
Utility Patent
2000-03-22
2001-01-02
Lo, Weilun (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
Hydraulic system
C123S1980DA
Utility Patent
active
06167853
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic control device for at least one lifting valve, and more particularly to a hydraulic control device having a valve stem associated with a first spring for loading in a valve-closing direction and a second hydraulically regulatable spring for loading in a valve-opening direction, and which is connected to a control piston arranged to be loaded hydraulically on two sides thereof, an operation of closing or opening the at least one lifting valve being capable of being triggered by an actuator of a central control unit.
DE 195 01 495 C1 discloses a valve control which guides a linearly moveable lifting valve. The valve control has a valve stem on which a helical compression spring acts in the valve-closing direction and an oil-pressure spring temporarily acts in the valve-opening direction. The valve control further has a control piston which is connected to the valve stem, is arranged in a working space, is capable of being loaded with a working fluid and which, in the region of each of its end positions, partially delimits a plunging space belonging to the working space and capable of being separated hydraulically from the latter. When the control piston has plunged into one of its plunging spaces, that is to say is located in the region of its end position, the plunging space is relieved of pressure, with the result that the pressure in the working space causes this valve position to be stabilized. If, however, the control piston and therefore the valve stem remain standing in an undefined middle position due to a malfunction, resetting and the elimination of this malfunction are possible only in a very complicated way.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a control device by which malfunctions can be compensated simply.
This object has been achieved according to the invention by providing that the second hydraulically regulatable spring means is assigned a hydraulically acting auxiliary control member which, in the event of an actuating operation of the actuator in the closing direction of the at least one lifting valve, relieves the second hydraulically regulatable spring means of pressure to below the actuating force of the first spring means. Consequently, the pressure of the second hydraulically regulatable spring means can be lowered separately and quickly until the compressive force of the first spring device predominates over that of the second hydraulically regulatable spring device. When the lifting valve is in any position, therefore, a movement for resetting the latter can be triggered by activating the auxiliary control member, without a reduction in the supply pressure having to be carried out. The auxiliary control member may be activated directly together with the activation of the actuator or indirectly as a result of the activation of the actuator and by virtue of the resulting actuating operation. This activation may take place mechanically, electronically, electrically, electromagnetically or pneumatically, as required, but preferably hydraulically. In the last-mentioned case, activation is preferably carried out via the same actuator which makes it possible to activate the control piston.
In an advantageous embodiment of the invention, the auxiliary control member has a 2/2-way valve function. This function can be implemented by particularly simple apparatus within the framework of the existing hydraulic system.
In an advantageous embodiment of the invention, the auxiliary control member is connected via control lines to a pressure supply line and a pressure relief line which are capable of being loaded by the actuator. The connection of the auxiliary control member to the existing hydraulic system can thereby be made particularly simply.
REFERENCES:
patent: 5193495 (1993-03-01), Wood III
patent: 5221072 (1993-06-01), Erickson et al.
patent: 5595148 (1997-01-01), Letsche et al.
patent: 5680841 (1997-10-01), Hu
patent: 5713315 (1998-02-01), Jyoutaki et al.
patent: 195 01 495 (1995-11-01), None
Daimler-Chrysler AG
Evenson, McKeown, Edwards & Lenahan P.L.L.C.
Lo Weilun
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