The invention relates to a device for shifting the position of a valve flap.
Such a device is known from U.S. Pat. No. 4,056,082. For space reasons it may be necessary to provide the vacuum box that is used with a coupling rod which makes possible an eccentric output of the adjusting force which is effected by the vacuum box. In accordance with the aforementioned publication, this is achieved in that the vacuum box is attached to an adjusting mechanism by means of which the output force can be displaced to another location. This, however, gives rise to additional manufacturing expense, which makes the apparatus more costly. In addition, the susceptibility of the apparatus to operational disturbances, e.g. by fouling of the linkage mechanism, is increased. In addition, additional space is required by the adjusting mechanism, and the apparatus is made heavier.
It is therefore the object of the invention to provide a device for shifting the position of a valve flap which will operate reliably, is simply constructed, has a low weight, requires little space, and at the same time makes possible an eccentric output of force. This object is achieved by the features of claim 1.
The substantial advantage of the invention is that the diaphragm device can be arranged at virtually any place in the vicinity of the valve flap, and the force is applied through the corresponding linkage. In particular, it is possible to arrange the diaphragm device such that it does not negatively affect the design of the overall air intake system but instead adapts itself to the form of the system.
In one practical embodiment of the invention the functions of the transmission of force and the mounting of the diaphragm are integrated in a single component. As a result, the cost of the manufacture of this diaphragm device is but slightly greater in comparison with conventional designs with a centralized application of force, which assures the cost of the proposed solution will be reasonable.
Another embodiment of the invention envisions constructing the transmission ratio of the operating rod to be variable, so that the range of movement of the diaphragm device can easily be adapted to the required flap movement.
It is advantageous to select the shape of the diaphragm such that the actuating force resulting from the pressure on the diaphragm corresponds as nearly as possible to the line of action of the traverse rod or to the point of linkage to the coupling rod. This construction has the advantage that the stress on the joint arranged on the hook plate in the housing of the diaphragm device is minimized and the pressure force of the diaphragm device is almost entirely available as an actuating force.
According to one embodiment of the invention, the diaphragm device is a vacuum box which can also have a diaphragm contour which differs from the conventional round shape. Such vacuum boxes are generally used in motor design; they are very reliable and inexpensive to manufacture.
To connect the coupling rod, traverse rod and valve flap and for the one-sided journaling to the hook plate of the asymmetrical vacuum box, ball joints are preferred. These are hooked or snapped to each other. In this way the assembly costs can be considerably reduced.
It is possible to additionally arrange a length compensating member in the traverse rod or the coupling rod and also to provide the diaphragm device or vacuum box with a return spring. These elements also result in an optimal adaptation to the system.
These and additional features of preferred embodiments of the invention will be found not only in the claims but also in the description and the drawings, the individual features being applicable individually or jointly in the form of subcombinations in embodiments of the invention and in other fields and may constitute advantageous as well as independently patentable embodiments, for which protection is hereby claimed.
The invention will be further explained hereinafter with reference to working embodiments.