Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Reexamination Certificate
2001-02-08
2002-05-14
Denion, Thomas (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
C123S090150
Reexamination Certificate
active
06386162
ABSTRACT:
BACKGROUND
The invention involves a variable valve drive for controlling the load of a positive ignition internal combustion engine. Moreover, the invention preferably involves a fully variable valve drive, which can effectuate a throttle-free load control for the internal combustion engine. Furthermore, this valve drive is installed in a position between one cam of a camshaft and at least one intake valve, where the intake valve adjoins immediately with a valve activation component, with a component designed for transmission, and with an adjustment mechanism designed to exert an influence on the lifting function of the transmission component. In addition, this transmission component—in a drive-like fashion—is built into position between the cam and the valve activation component, and has a first working surface that is opened up by the cam, as well as a second working surface that acts upon the valve activation component.
The advantages of throttle-free load control, over the sort of load control involving fully variable valve drives, are generally known to those skilled in the art. Through such “de-throttlization,” one succeeds in putting a stop to the losses that would otherwise come about due to suction—over a wide range of load conditions of the internal combustion engine.
Thus, DE 195 09 604 A1 discloses a fully variable finger lever drive, whose transmission component, formed as a further finger lever, can be adjusted from a point off center. The transmission component is opened by torsion leg spring which acts as a lost-motion spring.
Referring to this previously known valve drive it is disadvantageous for it to be built to undesirably high levels, as a result of the upright orientation of its transmission component, with the off-center point lying above. In exactly this cylinder head area, as a general rule, there is hardly any building space still in existence for the accommodation of the aforementioned building components. Consequently, in the event of the worst case scenario, costly modifications would have to be made in the area of the cylinder head cover, extending even into the area of the motor. It is further to be established that, in the process of being opened up and adjusted, the lever goes through a very complex course of movement, that is to be controlled only with great difficulty on the basis of intricate interpretation of a highly technical and mathematical nature.
Very often, with the fully variable systems described in the literature, the point in time at which the intake is shut off is also merely altered, with the simultaneous possibility of variation of a lift of the opened gas exchange valve.
SUMMARY
The object of the invention, therefore, is to create a valve drive of the aforementioned type, in connection with which the above-cited disadvantages have been eliminated.
In accordance with the invention, this task is accomplished by the fact that the transmission component is produced in such a way that it possesses two parts, and by the fact that it has one lever with the first working surface, and at least one catch with the second working surface, which catch is attached to the lever, at an end of the lever facing the valve activation component, by a pivot center, as well as adjoins with its second working surface at a contact surface of the valve activation component, whereby each catch has a third working surface for the respective adjustment mechanism, that extends on a side that faces away from the second working surface, which third working surface acts on a contact range of the adjustment mechanism during cam lifting, whose lifting is extended in the direction of the opening of the intake, and in connection with which the contact range is movable relative to the third working surface.
By these means, a valve drive is created—preferably of the fully variable type—that has a clearly lower height of construction as compared with the valve drive that was referred to in the introductory portion of the description. It is to be established, moreover, that it can be more simply constructed, with a clearly simplified course of movement, with adjustment and cam lifting. Consequently, the height of construction in the cylinder head area is either not increased at all, or—if increased—only to a minimal extent, so that costly modifications are not necessary in the construction components surrounding the interior combustion engine.
The fact that—through the way in which the contact range is installed on the adjustment mechanism—this contact range is not moved with the valve lifting constitutes a significant difference from the type forming the current state of the art. The contact range moreover is situated in a completely advantageous manner inside of, as well as underneath, a construction area that is canopied by the lever on the side of the valve. In this manner, a valve drive is created that is highly compact in its mode of construction.
Through the solution proposed by this invention, the duration of the opening of at least one opened up intake valve is amenable to being adjusted in a stepless fashion, and the height of the valve lifting is similarly susceptible to such stepless adjustment. Moreover, with respect to some further systems described in the current state of technology, it is advantageously the case, that even the time period for the opening of the intake can be retarded. In this context, it is suggested that the camshaft be equipped, in a familiar mode of construction, with a device for its relative rotation. In this manner, a backward adjustment that might perhaps be desired in the “early” direction can also be realized.
In a pivoting movement of the lever in the opening direction of the intake valve, the catch that is positioned for pivoting movement at the one end of the lever travels through a motion channel lying between a contact surface of the valve activation component and a contact range of the adjustment mechanism. In the motion channel, the catch can be forcibly shifted as to its position, as a function of a pivoting movement of the adjustment mechanism in the direction of the opening of the intake valve. This forcible pivoting movement in the aforesaid opening direction, consequently, results in the fully variable opening movement of the intake valve. In the zero lifting section, the catch merely rotates around the pivot center of the lever.
It is especially advantageous, in accordance with the invention, when for reasons of symmetry, one catch is installed on each of the two sides of the lever. Each of these catches then works with at least one gas exchange valve indirectly over each one of the finger levers. In a further development of this embodiment, the contact ranges of the two catches can be endowed with different lifting characteristics. This design can be utilized for the formation of a mixture-forming spin effect in the combustion chamber.
In an advantageous manner, the adjustment mechanism is adjoined directly to the lever and proceeds in a further advanced development of the invention, in accordance with which, the lever is formed as a rocker arm on the axis. It is also conceivable, however, that the adjustment mechanism might be formed as a construction component that is entirely removed and separated from the lever, which construction component can also have geometrical proportions that deviate from the finger form. It is only important that the adjustment mechanism should produce an adjustable pivoting movement for the catch in the direction of the opening of the intake valve.
In an advantageous manner, the zero lifting section of the contact range of the adjustment mechanism is formed with a sufficient length, that by the corresponding positioning of the catch to this area, either a zero lifting, or only a minimal lifting is produced at the intake valve. Consequently, the entire system can also be utilized for purposes of shutting off the valve, as well as for cylinder shut-off.
A highest valve lifting is produced at the intake valve, when the adjustment mechanism is rotated with reference to the third work
Corrigan Jaime
Denion Thomas
Ina Walzlager Schaeffler OHG
Volpe and Koenig P.C.
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