Abstract:
A mechanically controllable valve operating mechanism includes a cylinder head, a camshaft, a transmission arrangement mounted to move in the cylinder head via a bearing device. A gas exchange valve has the transmission arrangement act thereon. A valve-lift adjusting device comprises a rotatable adjusting element with an eccentric element having two base points and a peak contour, and at least one further eccentric element. The valve-lift adjusting device acts on the transmission arrangement so that different valve-lift positions are settable. The transmission arrangement is connected to the valve-lift adjusting device and to the camshaft. The at least one further eccentric element of the rotating adjusting element is arranged so that at least two peak contours are provided so that, depending on a rotational angle α of the rotating adjusting element, the eccentric element or the at least one further eccentric element engage with the transmission arrangement.

Description:
CROSS REFERENCE TO PRIOR APPLICATIONS 
       [0001]    This application is a U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2011/065044, filed on Aug. 31, 2011 and which claims benefit to German Patent Application No. 10 2010 048 709.0, filed on Oct. 19, 2010. The International Application was published in German on Apr. 26, 2012 as WO 2012/052216 A1 under PCT Article 21(2). 
     
    
     FIELD 
       [0002]    The present invention relates to a mechanically controllable valve operating mechanism having a gas exchange valve on which a transmission arrangement acts by means of an end surface, wherein the transmission arrangement is mounted movably in the cylinder head by means of bearing means, and wherein the transmission arrangement is operatively connected to a valve-lift adjusting means and a camshaft, wherein the valve-lift adjusting means has a rotatable adjusting element with an eccentric element which has two base points and a peak contour and which acts on the transmission arrangement counter to a pre-stressing force of a spring element in such a way that different valve-lift positions can be set. The present invention further relates to a mechanically controllable valve operating mechanism arrangement having a plurality of gas exchange valves arranged in line to which at least two in-line cylinders are assigned and a transmission arrangement is assigned to one gas exchange valve, wherein each transmission arrangement is mounted movably in the cylinder head by means of bearing means, and wherein each transmission arrangement is operatively connected to a respective valve-lift adjusting means and a camshaft, wherein each valve-lift adjusting means has a rotatable adjusting element with an eccentric element which has two base points and a peak contour and which acts on the transmission arrangement counter to a pre-stressing force of a spring element in such a way that different valve-lift positions can be set, such as zero lift, partial lift and full lift, wherein a plurality of adjusting elements can be driven by one driving element. 
       BACKGROUND 
       [0003]    EP 638 706 A1 describes a valve operating mechanism and a valve operating mechanism arrangement where the valve lift is controlled or regulated by an eccentric shaft rotatably supported in a cylinder head, which shaft acts on the transmission arrangement such that valve lifts between zero and maximum can be set in a simple manner. The combustion process can thereby be adjusted to the respective operating state of the internal combustion machine. DE 10 2004 003 324 A1 describes providing adjusting elements in a valve operating mechanism arrangement which can be adjusted independently with the purpose of deactivating individual cylinders for certain operating states. A valve operating mechanism is also described in EP 1 760 278 A2 which comprises an eccentric element showing different curves, in particular, for partial lift and full lift. The adjusting element here also allows for a zero lift curve. 
         [0004]    The above-described valve operating mechanisms/valve operating mechanism arrangements all have the disadvantage that an adjustment of the valve lift by means of the eccentric element curve must be performed very precisely. The variability of the valve lift settings is also very limited in a state of partial deactivation of cylinders, which in turn leads to increased fuel consumption and thus to higher emission values. 
       SUMMARY 
       [0005]    An aspect of the present invention is to provide a valve operating mechanism or a valve operating mechanism arrangement that avoids the above-described disadvantages. 
         [0006]    In an embodiment, the present invention provides a mechanically controllable valve operating mechanism which includes a cylinder head, a bearing device, a spring element, a camshaft, a transmission arrangement comprising an end surface. The transmission arrangement is mounted so as to be movable in the cylinder head via the bearing device. A gas exchange valve is configured to have the transmission arrangement act thereon via the end surface of the transmission arrangement. A valve-lift adjusting device comprises a rotatable adjusting element with an eccentric element having two base points and a peak contour, and at least one further eccentric element arranged in a circumferential direction. The valve-lift adjusting device is configured to act on the transmission arrangement counter to a pre-stressing force of the spring element so that different valve-lift positions are settable. The transmission arrangement is operatively connected to the valve-lift adjusting device and to the camshaft. The at least one further eccentric element of the rotating adjusting element is arranged so that at least two peak contours are provided so that, depending on a rotational angle α of the rotating adjusting element, the eccentric element or the at least one further eccentric element engage with the transmission arrangement. In this way, it is possible, firstly, to switch between at least three valve lift states in a simple and quick manner, it being irrelevant in which direction the adjusting element is turned. A low-cost solution is further provided that allows for a reduction of fuel consumption and emission values of an internal combustion engine by increasing the variability of a gas exchange valve. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The present invention is described in greater detail below on the basis of embodiments and of the drawings in which: 
           [0008]      FIG. 1  shows a perspective illustration of a valve operating mechanism arrangement of the present invention; 
           [0009]      FIG. 2  shows a sectional view of an eccentric shaft with two adjusting elements; and 
           [0010]      FIG. 3  shows a schematic illustration of the opening characteristic of the inlet valves with respect to the position of the adjusting elements. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    In an embodiment of the present invention, the base points of the respective eccentric elements can, for example, be spaced from each other by at least a zero lift curve. A plurality of zero lift curve shapes are thus created on the circumference of the adjusting element, thereby allowing a much more variable purposeful deactivation of cylinders. It can moreover be advantageous if the eccentric elements have different shapes and thus have respective valve lift curve sets that are different in form. It is also possible that at least one eccentric element is formed asymmetrically with respect to the respective peak point. In an embodiment of the present invention, the transmission arrangement includes at least one pivot lever and at least one rocker lever, wherein the pivot lever engages the gas exchange valve with a work curve and the rocker lever is operatively connected with the valve lift adjusting means and the camshaft and engages the pivot lever with a work curve. 
         [0012]    In an embodiment of the present invention, at least one adjusting element comprises at least one further eccentric element along its circumferential direction to provide at least two peak contours so that, depending on the rotation angle α of the adjusting element, different eccentric elements can pass into engagement with the transmission arrangement. Such an arrangement provides an economic and simple to manufacture possibility to deactivate individual valves, and thus cylinders, of an internal combustion machine in certain operating states. If the valve operating mechanism arrangement is configured such that the base points of the respective eccentric elements of the at least one adjusting element are spaced from each other by at least one zero lift curve, it is possible to realize the engine deactivation in a very variable manner. A large set of valve lift curves for the various load states is nevertheless still available to the cylinders operated. This variability is even increased if the eccentric elements have different shapes and/or at least one eccentric element is formed asymmetrically with respect to the respective peak point. In an embodiment of the present invention, a plurality of adjusting elements can be adapted to be driven by one driving element. 
         [0013]    In an embodiment of the present invention, a plurality of eccentric elements can be provided on one eccentric shaft. 
         [0014]    In an embodiment of the present invention, each transmission arrangement has at least one pivot lever and at least one rocker lever, where the pivot lever engages the gas exchanging valve by means of an end face and the rocker lever is operatively connected with the valve lift adjusting means and a camshaft and engages the pivot lever by means of a work curve. For an optimal combustion, it is advantageous if an even number of cylinders is provided, one half of the cylinders comprising gas exchange valves which each have one eccentric element more assigned thereto than the other half of the gas exchanging valves. On the outlet side, one half of the cylinders may further have gas exchanging valves that are operatively connected with a valve lift adjusting means, while the other half of the cylinders are adapted for conventional operation. 
         [0015]    The present invention will be described hereinafter with respect to the drawings. 
         [0016]      FIG. 1  illustrates an embodiment of a valve operating mechanism arrangement  10  of the present invention comprising a plurality of in-line gas exchange valves  12 ,  14 ,  16 ,  18 ,  20 ,  22 ,  24  and  26 . In the present case, two inlet gas exchange valves are respectively assigned to one cylinder of the internal combustion machine. In the present instance, the mechanically controllable valve operating mechanism arrangement  10  comprises four transmission arrangements  28 ,  29 ,  30 ,  31 ,  32 ,  33  and  34 ,  35 , each of which has assigned thereto two gas exchange valves  12 ,  14 ;  16 ,  18 ;  20 ,  22 ;  24 ,  26 . The transmission arrangements  28 ,  29 ,  30 ,  31 ,  32 ,  33  and  34 ,  35  are supported in a manner known per se in the cylinder head using bearing means. In  FIG. 1 , the bearing means  36 ,  38  are illustrated merely as examples for the bearing of a pivot lever  56  of the transmission arrangement  35 . The transmission arrangements  28 ,  29 ,  30 ,  31 ,  32 ,  33  and  34 ,  35  are further operatively connected with a camshaft  40  in a manner known per se. Each transmission arrangement  28 ,  29 ,  30 ,  31 ,  32 ,  33  and  34 ,  35  is controllable by means of adjusting elements  42 ,  43 ,  44 ,  45 ,  46 ,  47  and  48 ,  49  of a valve lift adjusting means  41  such that a smaller or a larger valve lift of the inlet valves  12 ,  14 ;  16 ,  18 ;  20 ,  22 ;  24 ,  26  can be set. In the present embodiment, the adjusting elements  42 ,  43 ,  44 ,  45 ,  46 ,  47  and  48 ,  49  are assigned to two inlet valves  12 ,  14 ;  16 ,  18 ;  20 ,  22 ;  24 ,  26 , respectively, and are designed as eccentric elements  60 ,  62  provided on an eccentric shaft  50 . In the present embodiment, the eccentric shaft  50  is adapted to be driven in a manner known per se by means of a driving element  52 . It is also possible to assign a transmission arrangement to each of the plurality of gas exchange valves. The driving element  52  may be a rotary drive running both clockwise and counterclockwise. The eccentric shaft  50  can thereby be driven such that, depending on the given position, the valve lift corresponding to the next operating state can be selected in a quick and precise manner by implementing the corresponding eccentric elements  60 ,  62 . Even rotation angles &gt;360° can thereby be realized. 
         [0017]    In the present embodiment, a mechanically controllable valve operating mechanism  54  comprises the transmission arrangement  35  and the gas exchange valve  26 . In this case, the transmission arrangement  35  is formed by a pivot lever  56  and a rocker lever  58 , the pivot lever  56  engaging the gas exchange valve  26  by means of an end face and the rocker lever  58  being operatively connected with the valve lift adjusting means  41  and the camshaft  40 . The adjusting element  48  of the valve lift adjusting means  41  here engages an engagement element, not illustrated in detail (a roller, for instance), of the rocker lever  58  against a pre-stressing force of a spring  55 . The rocker lever  58  engages the pivot lever  56  by means of a work curve not illustrated in detail. Guide rollers are arranged on the opposite side, which guide the rocker lever  58  in a slotted link. The guide rollers themselves are supported on a shaft that connects two adjacent rocker levers, with a roller being arranged on the shaft between the guide rollers, which is operatively connected with the camshaft. One cam of the camshaft is thus operatively connected with two transmission arrangements. With respect to the function and the operation of such a transmission arrangement, reference is made to DE 10 1140 635 A1. 
         [0018]    The present invention provides that individual adjusting elements, in the present embodiment the adjusting elements  42 ,  43  and  48 ,  49 , comprise a further eccentric element (see  FIG. 2 ).  FIG. 2  illustrates two sections through the eccentric shaft  50 ; one through the adjusting element  42  and the other through the adjusting element  47 . In the present embodiment, the adjusting element  42  for the gas exchange valve  12  thus comprises two eccentric elements  60 ,  62  which can influence the lift height of the gas exchange valve  12 . The eccentric elements  60 ,  62  each have a peak contour  61 ,  63 , where the peak contour  63  is in the form of a single peak. In the present context, a peak contour is defined as a finite sequence of peaks, i.e., also a single one. The peak contour triggers the respective full lift height of the gas exchange valve which is operatively connected with the respective eccentric element of an adjusting element via the transmission arrangement. The eccentric elements  60 ,  62  are shaped differently with respect to their height and the curve shape, the eccentric element  62  being symmetric with respect to its peak point  63 , while the eccentric element  60  is asymmetric, thereby leading to a flatter rise of the associated valve lift curve set. The associated peak point  63  or the peak contour  61  trigger the different full lift heights of the respective eccentric elements  60 ,  62 . 
         [0019]    In this embodiment, two base points  64  and  70  are further provided, where a base point is the point at which a zero lift curve passes into a partial lift curve. In the present embodiment, a zero lift curve  72  is thus formed between the respective base points  64  and  70 . Idling points  66  and  68  are further provided, at which an idling lift curve passes into a partial lift curve. The region between the idling points  66  and  68  is accordingly referred to as the idling lift curve  74  which is raised on the eccentric shaft by about 0.2 mm with respect to the zero lift curve. The idling lift curve  74  has the advantage that during control by means of this region or when passing through this region, the cylinder is not completely deactivated and therefore does not cool down. The second adjusting element  47  has only one eccentric element  76  which is formed congruently in shape and height with the eccentric element  62 . A zero lift curve  78  and an idling lift curve  80  are further provided that merge in the region of the peak contour  61  of the adjusting element  42  and which are defined by base points  82 ,  84  and an idling point  85 . 
         [0020]    It should be clear that all conceivable shapes that seem reasonable can be used for the eccentric elements. It is also possible that one adjusting element comprises more than two eccentric elements. In the present embodiment, the adjusting elements  44  and  46  for the valve lift adjustment of the gas exchange valves  16 ,  18 ,  20  and  22  comprise only one eccentric element  62  and thus correspond to the adjusting element known from the prior art. 
         [0021]      FIG. 3  schematically illustrates the different valve lift settings according to the present embodiment. The illustration shows four cylinders  86 ,  88 ,  90 ,  92  that comprise the inlet valves  12 ,  14 ,  16 ,  18 ,  20 ,  22 ,  24  and  26  shown in from  FIG. 1 . The adjusting elements  42  and  48  associated to the gas exchange valves  12 ,  14 , and  24 ,  26  here each have only one eccentric element  60 . If the eccentric shaft  50  is adjusted such that the eccentric elements  62  engage the respective rocker levers  58 , the valve lifts shown under I in  FIG. 3  can be set for the inlet valves  12 ,  14  and  24 ,  26 . The inlet valves  16 ,  18  and  20 ,  22  are deactivated. In order to make all inlet valves  12 ,  14 ,  16 ,  18 ,  20 ,  22 ,  24  and  26  open during the operation of the internal combustion machine, the eccentric shaft  50  is rotated such about an angle α that the eccentric elements  62  pass into engagement with the respective rocker levers  58 . The valve lifts schematically illustrated under II can thus be realized for the inlet valves  12 ,  14 ,  16 ,  18 ,  20 ,  22 ,  24  and  26 . The sense of rotation of the adjusting elements can thus be chosen such that the desired valve lift curve set can be controlled quickly and precisely. 
         [0022]    For a simple deactivation of cylinders, however, it is particularly advantageous with an even number of cylinders to assign adjusting elements to one half of the cylinders, which elements each have one eccentric element more than the other half of the cylinders. Of course, it is also possible to control the outlet valve by means of such an arrangement, in order to provide a corresponding deactivation of the outlet valves when the inlet valves are deactivated. 
         [0023]    The present invention is not limited to embodiments described herein; reference should be had to the appended claims.