DE19604991A1 - Variable valve control for internal combustion engine - Google Patents

Abstract

The variable valve control is for an internal combustion engine. It adjusts the rotary axis of the valve operating shaft drive (2), by a partial rotation of the bearing unit (1) round a fixed or moving axis. The partial rotation is through the changing torque of the valve shafts, in the working direction. The bearing unit (1) is fixed in two or more positions by a dedicated locking unit.

Description

The invention relates to a variable valve control, for internal combustion engines, by, in relation to the crankshaft, non-uniform rotation of the valve actuation shaft ( 4 ), caused by offset of the axis of the valve actuation shaft ( 4 ) and valve actuation shaft drive ( 2 ).

The variable valve control enables the opening and / or closing times te of inlet and / or outlet valves during operation to various Adjust operating points. This can increase efficiency, performance and the exhaust emissions of an internal combustion engine can be influenced positively.

It is known to shorten or lengthen the control times to select the valve actuation shaft ratio or the camshaft ratio during the valve lift smaller or larger 2. While the valve is closed, the gear ratio must be greater or less than 2 so that the average gear ratio is 2. The non-constant translation can be achieved by offsetting the axes of rotation of the valve actuating shaft ( 4 ), in FIG. 1 in the form of a camshaft ( 4 ), and camshaft drive ( 2 ). For this, if the camshaft ( 4 ) is immovably mounted, the bearing unit ( 1 ) of the camshaft drive ( 2 ) must be moved. For linear Ver push the bearing unit ( 1 ) and the camshaft drive ( 2 ) forces are required, which are known to be applied hydraulically with a device provided for this purpose. If the intake and exhaust cams are on a common shaft, the possible variation in the control time, with separate camshafts for intake and exhaust, is greatly reduced [Zeitschrift Automotive Engineering, October 1980, pages 120-124].

However, it is necessary if the adjustment is made even at full acceleration sufficient for a motor vehicle in 1st gear or when downshifting should be quick to provide large forces. Furthermore, it is not only for the forces required for adjustment, but also for control the adjustment requires a considerable amount of components.

The object of the invention is to vary the timing Inlet and outlet side, to allow adjustment in a large area to be done quickly between different tax times and the to be able to manufacture variable valve control at low cost.

The object is achieved in that a bearing unit ( 1 ) is rotatably mounted. By turning the bearing unit ( 1 ), the position of the axis of rotation of the camshaft drive ( 2 ) with respect to the axis of rotation of the camshaft ( 4 ) and thus the timing is changed. Except for desmodromic valve actuation and some other exceptions, the inlet and outlet valves are closed by cams and springs. The resulting moment of the inlet and exhaust camshafts, which changes in the direction of action, rotates the bearing unit ( 1 ) alternately to the right and left, unless the moment is compensated. The bearing unit ( 1 ) can be blocked in one position by means of a locking pin ( 6 ). After releasing the locking pin ( 6 ), the bearing unit ( 1 ) turns alternately to the left and right. In the same or another position, the storage unit ( 1 ) can be blocked again.

When the bearing unit ( 1 ) is eccentrically mounted, the inlet and outlet control times are adjusted in different, possibly advantageous, sizes.

In the unlocked position, the bearing unit ( 1 ) rotates alternately to the right and left. If an end stop is provided for the bearing unit ( 1 ), shocks are caused by forces, which require adequate dimensioning of the components. The use of shock insulation elements, vibration dampers and / or friction damping means that the dimensions can be made weaker and therefore more economical.

The advantages achieved with the invention are in particular that the large adjustment range of the control times the internal combustion engine can be better adapted to different operating points. Known Variable fuel control can usually reduce fuel consumption and exhaust emissions are reduced, the usable speed range is broadened the starting behavior are improved, the idling speed is reduced and be stabilized and performance increased. With changing Speeds, the adjustment of the timing can be done quickly. Costs it is favorable to dispense with a special adjustment device.

An embodiment of the invention is shown in the drawing and will described in more detail below.

It shows

Fig. 1 len an embodiment of the variable valve control in a diagrammatic representation for a single-cylinder engine with two overhead Nockenwel.,

The holder ( 5 ) shown in Fig. 1 is firmly connected to the motor housing. The bearing unit ( 1 ) is rotatably mounted in the holder ( 5 ). The camshaft drives ( 2 and 7 ) for the intake and exhaust side are mounted in the bearing unit ( 1 ). The control chain ( 8 ) shown symbolically drives the camshaft drives ( 2 and 7 ). The camshaft ( 4 ) is driven via the connecting link ( 3 ). The axis of rotation of the camshaft ( 4 ) cannot be changed. By rotating the bearing unit ( 1 ), the axis of rotation of the camshaft drive ( 2 ) can be moved out of the axis of rotation of the camshaft.

If the axes of rotation of the camshaft ( 4 ) and camshaft drive ( 2 ) are not identical, the camshaft ( 4 ) rotates non-uniformly with respect to the camshaft drive ( 2 ) and changes the original timing. In addition, the phase of the control time is also changed by the rotary movement of the bearing unit ( 1 ), since this changes the position of the camshaft drive ( 2 ) with respect to the crankshaft. The connection ( 3 ) allows the axes of rotation of the camshaft ( 4 ) and camshaft drive ( 2 ) to be offset and transmits forces between the two. In operation, the bearing unit ( 1 ) rotates alternately to the right and left, since the cams on the trailing flank exert an opposite moment on the bearing unit ( 1 ). With one of the locking pins ( 6 ), the bearing unit ( 1 ) can be fixed in one of the three holes in the holder ( 5 ) via the hole attached to it. After loosening the fixation, the bearing unit ( 1 ) turns again to the right and left and it can be fixed in the same or another hole in the holder ( 5 ). All three fixings generate different timing. Since the bearing unit ( 1 ) rotates once to the right and once to the left for each intake and exhaust camshaft revolution, it can be switched quickly between the various control times.

Claims (3)

1.Variable valve control, for internal combustion engines, by, in relation to the crankshaft, non-uniform rotation of the valve actuation shaft ( 4 ), caused by offset of the axis of rotation of the valve actuation shaft ( 4 ) and valve actuation shaft drive ( 2 ), characterized in that the adjustment of the axis of rotation of the valve actuation shaft drive ( 2 ) by a partial rotation of the bearing unit ( 1 ) about a fixed or movable axis and the partial rotation of the bearing unit ( 1 ) by the moment exerted by the valve actuating shaft or shafts, which changes in the effective direction, and the determination of the bearing unit ( 1 ) in two or more positions by a special locking device. 2. Variable valve control according to claim 1, characterized in that the bearing unit ( 1 ) is rotatably mounted eccentrically. 3. Variable valve control according to one of claims 1 or 2, characterized in that for damping impacts of the bearing unit ( 1 ) against end stops on the non-rotatable part of the cylinder head shock insulation elements between the bearing unit ( 1 ) and the cylinder head and / or vibration damper between the bearing unit ( 1 ) and cylinder head are provided and / or the bearing of the bearing unit ( 1 ) is preloaded to increase friction.