Abstract:
Impurities of a lubricant in traditional camshaft adjusters can cause a problem, leading to impairment in the function and service life of the camshaft adjuster. In order to address this, flow channel areas are provided in the lubricant circuit, which include a dead chamber ( 37 ) where impurities can be deposited as a result of centrifugal force. Alternatively or additionally, a labyrinth is used to deposit impurities.

Description:
BACKGROUND 
       [0001]    The invention relates to a camshaft adjuster for an internal combustion engine, in which lubrication is performed via a flow of lubricant, especially according to the preamble of Claim  1 ,  3 , or  5 . 
         [0002]    Camshaft adjusters can be roughly classified as follows: 
         [0003]    A. Phase adjusters with a control element, that is, a functional unit, which engages in the mass flow or energy flow, for example, hydraulically, electrically, or mechanically, and rotates with gear elements of the camshaft adjuster. 
         [0004]    B. Phase adjusters with a separate setting element, that is, a functional unit, in which the control parameter required for the control method of the control element is formed from the controller output parameter, and a separate control element. Here, there are the following structural forms: 
         [0005]    a. Phase adjusters with a co-rotating actuator and a co-rotating control element, for example, a step-up ratio gear, whose adjustment shaft can be advanced by a co-rotating hydraulic motor or centrifugal force motor and can be reset by a spring. 
         [0006]    b. Phase adjusters with a co-rotating control element and a stationary, engine-fixed actuator, for example, an electric motor or an electrical or mechanical brake, see also DE 100 38 354 A1, DE 102 06 034 A1, EP 1 043 482 B1. 
         [0007]    c. Phase adjusters with a direction-dependent combination of solutions according to a. and b., for example, an engine-fixed brake, in which part of the brake power is used for adjustments toward an advanced position, in order to tension a spring, which allows resetting after the brake is deactivated, see also DE 102 24 446 A1, WO 03-098010, US 2003 0226534, DE 103 17 607 A1. 
         [0008]    In systems according to B.a. to B.c., actuators and control elements are connected to each other by an adjustment shaft. The connection can be switchable or non-switchable, detachable or non-detachable, lash-free or with lash, and flexible or stiff. Independent of the structural form, the adjustment energy can be realized in the form of supply through a drive output and/or brake output, as well as with the use of leakage power of the shaft system (e.g., friction) and/or inertia and/or centrifugal force. Braking, advantageously in the adjustment direction of “retarded” can also be realized under the full use or shared use of the friction power of the camshaft. A camshaft adjuster can be equipped with or without mechanical limiting of the adjustment range. As a gear drive in a camshaft adjuster, one-stage or multiple-stage triple-shaft gear drives and/or multiple links or coupling gears are used, for example, in structural form as a wobble-plate gear drive, eccentric gear drive, planetary gear drive, undulating gear drive, cam-plate gear drive, multiple-link or linked gear drive, or combinations of the individual structural forms in a multiple-stage construction. 
         [0009]    For operation of the camshaft adjuster, a lubricant must be fed to lubricating positions, especially bearing positions and/or rolling toothed sections, wherein the lubricant is used for lubricating and/or cooling components of the camshaft adjuster that can move relative to each other. For this purpose, the camshaft adjuster has a lubricant circuit, which can be coupled, for example, with the lubricant circuit of the internal combustion engine. 
         [0010]    From DE 696 06 613 T2 it is known that a control fluid for a camshaft adjuster with a vane-cell construction can contain impurities. If such impurities settle between vanes and a wall of a chamber defining an end position of the vane, this produces a change in the end position of the vane. This has the result that a maximum advanced or retarded state of the camshaft adjuster can no longer be reached exactly, which can make it impossible to control the valve timing as desired. In addition, impurities can get between the upper section of a vane and an outer peripheral wall of the chamber, which causes the control forces for actuating the camshaft adjuster to be increased and/or the fluid tightness between pressure chambers arranged on opposite sides of the vane becomes worse. This can lead to a decrease in the dynamic response of the camshaft adjuster. 
         [0011]    Furthermore, it is known from DE 40 07 981 C2 to connect a damper, which is used for receiving or absorbing changes in rotational moment of the camshaft, between a belt pulley and a camshaft in a camshaft adjuster. Here, the damper can be formed as a viscosity damper, which includes annular labyrinth channels filled with a viscous fluid. 
       SUMMARY 
       [0012]    The present invention is based on the objective of providing a camshaft adjuster, which distinguishes itself by high operational reliability and/or functionality even for a contaminated lubricant in the lubricant circuit. 
         [0013]    According to the invention, the objective is met by the features of Claim  1 . Another solution for meeting the objective forming the basis of the invention is given according to the features of Claim  3 . An alternative or cumulative solution for meeting the objective forming the basis of the invention is given by the features of Claim  5 . 
         [0014]    The invention is based on the knowledge that impurities can lead to functional disruptions in the adjustment mechanism. The impurities can involve, e.g., particles or deposits in the lubricant or residues from combustion and contaminants contained in the motor oil. The functional disruptions or negative effects caused by the contaminants can involve, for example, 
         [0015]    those according to DE 696 06 613 T2, 
         [0016]    blockage of a lubricant channel, 
         [0017]    change in the flow cross section of a lubricant channel, 
         [0018]    increased wear, and/or 
         [0019]    higher leakage power due to contaminant particles in the functional surfaces during adjustment. 
         [0020]    Furthermore, under some circumstances, the impurities in the adjustment mechanism are, for all practical purposes, centrifuged, so that a gear drive according to the state of the art can become silted or contaminated. 
         [0021]    Furthermore, one construction of the invention touches on the knowledge that flow channel regions are formed in components of the camshaft adjuster that are set in rotation during the course of the drive movement of the camshaft and/or during the course of the adjustment movement of the camshaft adjuster. This has the result that impurities, which are located in the lubricant and which have a higher density than the density of the lubricant itself, move in the radial direction away from the rotational axis of the component containing the flow channel and settle outside of the rotational axis in the radial direction at a boundary of the flow channel region. 
         [0022]    On one hand, this can have the result that the impurities settle permanently in the flow channel region, by which the structurally defined and, under some circumstances, purposefully selected cross section of the flow channel region changes. This can cause a change in the flow relationships that negatively affects the function of the camshaft adjuster. 
         [0023]    On the other hand, it is also possible that impurities that settle only temporarily will become entrained by the flow of lubricant and delivered to functional surfaces of the camshaft adjuster, at which these impurities lead to negative effects. Here, settling at the boundary of the flow channel region can also cause a “formation of clumps,” which has the result of amplifying undesired negative effects. 
         [0024]    According to the invention, the knowledge explained above can be used in such a way that a dead space is provided, which is used purposefully for receiving the undesired impurities of the lubricant. The dead space is here in lubricant connection with an inlet opening, especially for feeding, as well as an outlet opening, especially for forwarding the lubricant to a functional surface. Furthermore, the dead space is formed, at least partially, in the radial direction outside of the rotational axis of the affected component with respect to the inlet opening and the outlet opening. Such a construction has the result that for a flow of lubricant through the flow channel region from the inlet opening to the outlet opening, the impurities are accelerated in the radial direction outward into the dead space due to centrifugal acceleration and can be deposited in this space. In this way it is avoided that the impurities are delivered to other functional surfaces via the outlet opening. 
         [0025]    Advantageously, the dead space between the inlet opening and outlet opening in the flow channel region represents a cross-sectional expansion of this region, which, under some circumstances, has the additional result that the flow rate of the lubricant in the region of the dead space and between the inlet opening and outlet opening is reduced, and the centrifugal acceleration and the supply of impurities into the dead space can be amplified. 
         [0026]    The dead space according to the invention can involve, for example, a cross-sectional expansion of the flow channel, pockets on the outside in the radial direction, a peripheral groove, a recess oriented outward in the radial direction, or the like. If movement of the impurities in the peripheral direction about the rotational axis is to be prevented, additional separating walls oriented in the radial direction can be provided for dead spaces running in the peripheral direction. 
         [0027]    The dead space can have a suitable construction for receiving impurities during the entire service life of the camshaft adjuster. In an alternative construction, the dead space has an additional outlet opening outside of the inlet opening and the outlet opening in the radial direction. This additional outlet opening is used for the discharge of lubricant with an increased concentration of impurities and/or the discharge of impurities arranged in the dead space. Accordingly, the regions of the dead space lying inside in the radial direction are used for forwarding the lubricant to the outlet opening, from which the lubricant is led to the functional surfaces and the control unit, while the region of the dead space on the outside in the radial direction is used for collecting and discharging lubricant. Here, the lubricant can be discharged to other sub-regions of the camshaft adjuster, for which the risk of negative effects due to impurities is at least reduced, so that, in the region of the dead space, the lubricant flow is branched. Alternatively, it is also possible that via the additional outlet opening, a type of “bypass” is formed, by which centrifuged lubricant, under some circumstances, with an increased concentration of impurities, is led past the functional surfaces of the camshaft adjuster or is fed to a special device for disposing of the impurities. 
         [0028]    For another solution for meeting this objective based on the invention, a dead space is provided, which is arranged in the installed state of the camshaft adjuster at a geodetically lower height than the inlet opening and the outlet opening. In this case, the feeding effect of the impurities into the dead space does not touch upon centrifugal force due to the rotation of the flow channel region, but instead on the force of gravity of the impurities, which has the result that the impurities are deposited downward, that is, into the dead space. 
         [0029]    For creating a feeding effect through the additional outlet opening for the lubricant with the impurities, centrifugal acceleration can be used. In this case, it is provided that a channel oriented outward in the radial direction is allocated to the additional outlet opening. Alternatively or additionally, the feeding effect through the outlet opening can be used at a pressure drop in the dead space relative to a downstream channel allocated to the outlet opening. 
         [0030]    For the solution described above, the dead space has an additional outlet opening at a lower geodetic height than the inlet opening and the outlet opening, for the case that the lubricant with the impurities in the dead space is to be discharged during the operation of the camshaft adjuster, wherein, in this case, a feeding effect through the additional outlet opening is achieved by the force of gravity of the lubricant and the impurities. 
         [0031]    Another solution to meeting the objective that forms the basis of the invention is given in such a way that the flow channel region has a labyrinth region. 
         [0032]    In this case, the flow of lubricant is led through a labyrinth. This can have the result that the lubricant 
         [0033]    is decelerated or accelerated again or 
         [0034]    deflected several times. 
         [0035]    Impurities with higher density than the lubricant are, under some circumstances, not accelerated again as quickly as the lubricant itself or not deflected quickly, so that the impurities can be deposited in the region of the labyrinth. This gives a reliable option for the separation of the impurities. In this context, a labyrinth is understood to be, in particular, 
         [0036]    a back and forth, 
         [0037]    meander-shaped, 
         [0038]    zigzag-shaped profile or 
         [0039]    profile with curves of different signs 
         [0000]    with arbitrary orientation to the longitudinal axis of the camshaft adjuster, but advantageously with radial or axial orientation to this axis. 
         [0040]    Advantageously, the outlet opening of the labyrinth region and/or the inlet opening of the labyrinth region is located on the inside in the radial direction with respect to the rotational axis of the flow channel region and/or at a greater geodetic height. Furthermore, another outlet opening can also be arranged in the region of the labyrinth region, advantageously at the lower geodetic height or at a large radial distance from the rotational axis, in order to discharge lubricant with impurities. 
         [0041]    The dead spaces involve, in particular, spaces, in which the lubricant is more or less at rest, so that the dead spaces form regions, which do not represent direct flow-through zones of the lubricant. Advantageously, such dead spaces can also be arranged in the gear drive itself. 
         [0042]    The dead space is advantageously arranged as a radial groove in the region of a central, end-face borehole of the camshaft and/or a hollow shaft holding an end face of the camshaft. 
         [0043]    Advantageous improvements of the invention emerge from the claims, the description, and the drawings. The advantages noted in the introduction of the description for features and combinations of several features are merely examples, without these having to be necessarily realized by embodiments according to the invention. Additional features are to be taken from the drawings—in particular, the illustrated geometries and the relative dimensions of several components to each other, as well as their relative arrangement and effective connection. The combination of features of different embodiments of the invention or of features of different claims is similarly possible deviating from the selected associations of the claims and is suggested with this reference. This also relates to features that are shown in separate drawings or are named in their description. These features can also be combined with features of different claims. Likewise, features listed in the claims can be left out for other embodiments of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0044]    Additional features of the invention emerge from the following description and the associated drawings, in which embodiments of the invention are shown schematically. Shown are: 
           [0045]      FIG. 1  a schematic diagram of a camshaft adjuster, 
           [0046]      FIG. 2  a schematic diagram of a camshaft adjuster with a wobble-plate gear drive, 
           [0047]      FIG. 3  a camshaft adjuster in a schematic diagram with a lubricant circuit, 
           [0048]      FIG. 4  a schematic diagram of a camshaft adjuster with a lubricant circuit, in which a filter element is integrated, 
           [0049]      FIG. 5  a view of a camshaft adjuster in semi-longitudinal section with a dead space for the deposition of contaminant particles, 
           [0050]      FIG. 6  a schematic diagram of a camshaft adjuster with a lubricant circuit, which is equipped both on the input side and also on the output side with a throttle and a diaphragm, 
           [0051]      FIG. 7  a longitudinal section view of a camshaft adjuster with guidance of the lubricant into a flow channel, 
           [0052]      FIG. 8  a longitudinal section view of a camshaft adjuster, in which two diaphragms are connected one after the other in a flow channel, 
           [0053]      FIG. 9  a longitudinal section view of a camshaft adjuster with a flow element, which is set on a central screw and which forms a diaphragm with an inner casing surface of the camshaft, 
           [0054]      FIG. 10  a longitudinal section view of a camshaft adjuster with a diaphragm formed between a hollow shaft and a central screw, 
           [0055]      FIG. 11  a longitudinal section view of a camshaft adjuster with the feeding of a lubricant via a transfer cross section from an outlet opening of the cylinder head to an inlet cross section of the camshaft, 
           [0056]      FIG. 12  a longitudinal section view of another construction of a lubricant feed to a camshaft and to a camshaft adjuster, 
           [0057]      FIG. 13  a longitudinal section view of another construction of a lubricant feed to a camshaft and to a camshaft adjuster 
           [0058]      FIG. 14  a longitudinal section view of another construction of a lubricant feed to a camshaft and to a camshaft adjuster, 
           [0059]      FIG. 15  a longitudinal section view of another construction of a lubricant feed to a camshaft and to a camshaft adjuster, 
           [0060]      FIG. 16  a longitudinal section view of a camshaft adjuster with different examples for an arrangement of diaphragms or throttles for influencing the flow of a lubricant, 
           [0061]      FIG. 17  a perspective view of a camshaft adjuster with openings of a housing of the gear drive for passage of the lubricant in the form of droplets, lubricant mist, or sprayed lubricant, 
           [0062]      FIG. 18  a perspective view of the camshaft adjuster according to  FIG. 17  with other options for openings, 
           [0063]      FIG. 19  a view of a camshaft adjuster in the installed state with options for lubrication via droplets, a lubricant mist, and/or sprayed lubricant, and 
           [0064]      FIG. 20  a side view of a camshaft adjuster in the installed state having a drop plate, on which droplets of an oil mist settle and drop in the direction of the interior of the camshaft adjuster. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0065]    In the figures, components that correspond with respect to form and/or function are to some extent provided with the same reference symbols. 
         [0066]      FIG. 1  shows in a schematic diagram a camshaft adjuster  1 , in which, in a gear drive  2 , the movement of two input elements, here a drive wheel  3  and an adjustment shaft  4  (also called wobble plate), is superimposed on an output movement of an output element, here a driven shaft  5  locked in rotation with a camshaft or the camshaft  6  directly. The drive wheel  3  is in driven connection with a crankshaft of the internal combustion engine, for example, via a traction element, such as a chain or a belt, or a suitable toothed section, wherein the drive wheel  3  can be formed as a chain or belt wheel. 
         [0067]    The adjustment shaft  4  is driven by an electric motor  7  or is in active connection with a brake. The electric motor  7  is supported relative to the surroundings, for example, the cylinder head  8  or another engine-fixed part. 
         [0068]      FIG. 2  shows an example construction of a camshaft adjuster  1  with a gear drive  2  in a wobble-plate construction. A housing  9  is locked in rotation with the drive wheel  3  and is sealed in an axial end region by a sealing element  10  relative to the adjustment shaft  4 . In the opposite axial end region, the housing  9  is sealed with a sealing element  11  relative to the cylinder head  8 . An end region of the camshaft  6  projects into an inner space  36  formed by the housing  9  and the cylinder head  8 . Arranged in the inner space are furthermore, an eccentric shaft  13  connected via a coupling  12  to the adjustment shaft  4 , a wobble plate  15  supported by a bearing element  14 , for example, a roller bearing, and a hollow shaft  16 , which is supported by a bearing element  17 , for example, a roller bearing, on the inside in a central recess of the eccentric shaft  13  and carries a driven conical gear wheel  18 . The driven conical gear wheel  18  is supported by a bearing  19  relative to the housing  9 . In the interior, the housing  9  forms a drive conical gear wheel  20 . The wobble plate  15  has suitable toothed sections on opposite end faces. The eccentric shaft  13  with the bearing element  14  and wobble plate rotates about an axis inclined relative to a longitudinal axis  21 - 21 , so that the wobble plate meshes on sub-regions offset in the peripheral direction relative to each other, on one hand, with the drive conical gear wheel  20  and, on the other hand, with the driven conical gear wheel  18 , wherein a step-up or step-down ratio is given between the drive conical gear wheel and driven conical gear wheel. The driven conical gear wheel  18  is locked in rotation with the camshaft  6 . 
         [0069]    For the embodiment shown in  FIG. 2 , the hollow shaft  16  with the driven conical gear wheel  18  is screwed via a central screw  22 , which extends through the hollow shaft  16 , to the camshaft  6  on the end. Lubrication with a lubricant, especially oil, is necessary in the region of the lubricating positions  23 ,  24 , which can involve, for example, 
         [0070]    the contact surfaces between the drive conical gear wheel  20  and wobble plate  15 , 
         [0071]    the contact surface between the wobble plate  15  and driven conical gear wheel  18 , 
         [0072]    the bearing  19 , 
         [0073]    bearing element  14 , and/or 
         [0074]    bearing element  17 . 
         [0075]    Here, a continuous, cyclical, pulsing, or intermittent feed and/or forwarding of a lubricant via the lubricant channels is realized. By means of a feed recess  25  of the cylinder head  8 , the lubricant is fed to a flow channel  26  of the camshaft  6 , which communicates with a flow channel  27 , which is formed with a hollow cylindrical shape between an inner casing surface  28  of the hollow shaft  16  and an outer casing surface  29  of the central screw  22 . Using radial boreholes  30  of the hollow shaft  16 , the lubricant can emerge from the flow channel  27  outward in the radial direction and can be fed to the lubricating positions. 
         [0076]      FIG. 3  shows a schematic lubricant circuit. The lubricant is fed from a reservoir  31 , for example, an oil pan or an oil tank, via a pump  32 , for example, a motor-oil pump, through a filter  33 , in particular, a motor-oil filter, to the supply recess  25  and the flow channel  26  of the camshaft  6 . The lubricant leaves the camshaft adjuster  1  or the housing  9  of the camshaft adjuster via an outlet opening  34  and is fed back into the reservoir  31 . 
         [0077]    In contrast to the embodiment according to  FIG. 3 , the schematic lubricant circuit according to  FIG. 4  has an additional filter element  35 . The filter element  35  is advantageously allocated to the camshaft adjuster  1  and is arranged, for example, after a branch of the lubricant circuit to other components to be lubricated and allocated exclusively to the branch of the lubricant circuit that is used for lubricating the camshaft adjuster. Here, the filter  35  is arranged as close as possible to the installation position of the camshaft adjuster  1  or in the camshaft adjuster itself. The filter element  35  can be used to keep processing residue in the flow channels, which are arranged upstream of the filter element  35 , away from the flow channels of the cylinder head and the camshaft. Furthermore, fabrication residue and contaminant particles in the lubricant can be kept away from the gear drive  2  of the camshaft adjuster  1 . Furthermore, a diaphragm characteristic or a throttle effect of the filter element  35  can be used selectively, in order to influence the pressure, the volume flow, and the velocity of the lubricant. The filter element  35  is advantageously to be implemented in such a way that it cannot become blocked or clogged due to the flow relationships at the maximum contamination to be expected with particles and contaminants during the runtime of the camshaft adjuster. For example, the arrangement in a rising line and/or as a secondary current filter is advantageous. 
         [0078]    The filter element  35  can be constructed, e.g., as 
         [0079]    a screen, 
         [0080]    a ring filter, 
         [0081]    a plug-in filter, 
         [0082]    a shell filter, 
         [0083]    filter plates, 
         [0084]    filter net, or 
         [0085]    sintered filter. 
         [0086]    According to  FIG. 5 , lubricant is fed into an inner space  36  of the housing  9 , for example, according to the embodiments described above, wherein, in the inner space  36 , the lubricant comes into contact with the lubricating positions. The inner space  36  is in lubricant connection with a dead space  37 , which is arranged at a position of the inner space  36  farthest removed in the radial direction. A connection of the dead space  37  to the inner space  36  can be formed over a large surface via transfer cross sections or via separate channels, by which lubricant can be fed to and also discharged from the dead space  37 . 
         [0087]    For the embodiment shown in  FIG. 5 , the dead space  37  is constructed as a surrounding ring channel. A dead space  37  involves, in particular, a space, in which the lubricant moves with minimal velocity or is almost at rest, so that the dead space  37  is not arranged in a direct, maximum flow-through zone of the lubricant. In the dead space  37 , due to the rotation of the housing  9 , the lubricant is exposed to a centrifugal force, through which heavy components and particles suspended in the lubricant are pressed outward and can be deposited on a wall  38  on the outside in the radial direction and are not led back to a lubricating position. It is further possible that the annular dead space  37  is separated in the peripheral direction by intermediate walls, so that, in the peripheral direction, several individual chambers are formed, by which it is avoided that in the dead space  37 , the lubricant can move in the peripheral direction relative to the housing  9 . Settling of contaminants is thus realized analogous to a rotating centrifuge. 
         [0088]    Dead spaces according to the dead space  37  can be arranged at any position in the gear drive, as well as in the region of the camshaft, by which it can be achieved that important functional surfaces, for example, in the direct neighborhood of the dead spaces, are not “silted up” due to centrifuged contaminants in the gear drive. The centrifugal effect is amplified by an increase in the distance of the dead spaces from the longitudinal axis  21 - 21 . 
         [0089]    According to a first construction, the dead space has no additional outflow, so that centrifuged contaminant particles are deposited permanently in the dead space  37 . According to the preferred construction shown in  FIG. 5 , the dead space has at least one additional outlet opening  39 ,  40 , wherein the outlet opening  39  is oriented in the axial direction and the outlet opening  40  is oriented in the radial direction. Due to the radial centrifugal force and/or the pressure ratios in the dead space  37  in comparison with the surroundings of the camshaft adjuster  1 , the lubricant with deposited contaminant particles moves in the radial direction out of the outlet opening  40 , wherein the feeding of the contaminant particles is supported by the centrifugal effect. Alternatively, feeding through the outlet opening  39  is realized exclusively through the pressure difference in the dead space  37  on one side and in the surroundings of the camshaft adjuster  1  on the other side. 
         [0090]    For an alternate construction, contaminants are separated in such a way that the lubricant is guided in a flow channel with a labyrinth-like or zigzag-shape construction. Contaminant separation through such a labyrinth-like contaminant separator touches upon the different inertia of the lubricant and interfering particles in the lubricant. In particular, for high flow rates, a strong deflection of the lubricant flow can lead to the result that the particles are not deflected, but instead are deposited at the borders of the labyrinth. For the case that individual channels of the labyrinth are oriented in the radial direction, deposition in the labyrinth on surfaces on the outside in the radial direction can take place in such channels, as well as similarly in axial channels, due to the centrifugal force described above. An alternative or additional separating effect can be produced when the lubricant is decelerated and accelerated, wherein the lighter lubricant can be accelerated more easily, while contaminant particles remain behind. 
         [0091]    In additional to generating the centrifugal effect due to rotation of the housing  9  or other parts of the camshaft adjuster  1 , the centrifugal effect can be generated at least partially in such a way that the flow channels guiding the lubricant are oriented in a circular or spiral construction, so that a deposit can form on the outer boundaries of the flow channels just due to the movement of the lubricant through the curved flow channels. 
         [0092]    Deviating from the embodiments shown in  FIGS. 3 and 4  for a lubricant circuit, the schematic lubricant circuit shown in  FIG. 6  has an input-side diaphragm  41  and also an input-side throttle  42  and an output-side diaphragm  43  and also an output-side throttle  44 . The diaphragms  41 ,  43  and throttles  42 ,  44  form flow elements for influencing the flow ratios in the lubricant circuit. The flow elements named above are allocated to a parallel lubricant path, which applies a force exclusively to the camshaft adjuster  1 . Advantageously, the flow elements are arranged close to the camshaft adjuster  1  or is integrated at least partially into this adjuster, the camshaft, or a cylinder head in the region of a bearing position for the camshaft. 
         [0093]    Through the use of the diaphragms  41 ,  43  and throttles  42 ,  44 , the volume flow to the camshaft adjuster is throttled. Additional throttling can be produced through the use of the filter element  35 . Advantageously, the filter element is arranged in the flow direction upstream of the flow elements, so that the flow elements do not become blocked by particles or clogged over the course of time. 
         [0094]    In addition to the use of flow elements with constant flow characteristics, a flow element that is continuous or that can be changed in steps can be used. The use of a flow element, whose flow effect is variable 
         [0095]    as a function of an engine rotational speed, 
         [0096]    coupled with a feeding volume of the pump  32 , and/or 
         [0097]    as a function of the temperature of the camshaft adjuster  1  or the lubricant 
         [0000]    is possible, wherein the mentioned changes can be generated automatically in a mechanical way or by a suitable control or regulating device, which acts on the flow element. 
         [0098]    The flow element is changed in such a way that, for example, the volume flow of the lubricant is held to a constant value independent of the temperature of the lubricant. It is also possible that the volume flow is increased or decreased due to an effect of the flow element in operating regions, in which there are higher or lower lubricant or cooling requirements. 
         [0099]    For the construction of the flow elements in the form of throttles  42 ,  44  and diaphragms  41 ,  43 , under some circumstances, embodiments are to be used, in which ring gaps or annular cross sections are used instead of boreholes with, for example, a circular cross sectional surface, because, under some circumstances, a borehole can be more easily blocked than a ring gap. 
         [0100]    For the embodiment shown in  FIG. 7 , lubricant is fed via several boreholes  45  of the camshaft  6 , wherein the boreholes  45  are inclined relative to the longitudinal axis  21 - 21  and the radial orientation. The camshaft  6  has an end-face blind borehole  46 , which transfers with a conical chamfer  47  into a thread for receiving the central screw  22 . The boreholes  45  open into the chamfer  47 . In the end region opposite the chamfer  47 , the boreholes  45  are fed with lubricant from a supply groove of the cylinder head  8 . A groove  48  surrounding in the radial direction is formed with the rectangular geometry shown in the longitudinal section approximately in the center in the borehole  45 . 
         [0101]    One part of the lubricant fed to the groove  48  via the borehole  45  and borehole  46  is led via an axial borehole  49  of the camshaft  6 , which opens into the groove  48 , and an axial borehole  50  of the housing  9  with a certain amount of overlap, but offset in the radial direction, in the inner space of the gear drive  2  to the lubricating positions, for example, to the bearing element  17 , the bearing element  14 , the rolling toothed connections of the wobble plate  15 , and/or the bearing  19 . 
         [0102]    The other part of the lubricant fed to the groove  48  is led via a flow channel  51  with a circular ring-shaped cross section and formed between the inner casing surface of the hollow shaft  16  and the outer casing surface of the central screw  22  to at least one radial borehole  52  to a lubricating position, for example, the bearing position  17  or in the inner space of the gear drive  2 . The groove  48  is constructed with a radial projection, which extends over the borehole  49 , so that a peripheral, ring-shaped dead space  37  is formed on the outside in the radial direction. Between the boreholes  49 ,  50 , a transfer region  53  can be formed in the shape of a recess, a radial groove, or the like, in order to allow transfer between the boreholes  49 ,  50  that are offset relative to each other in the radial direction. In the form of the boreholes  49 ,  50  that are not aligned with each other, for a partial overlap of the boreholes, a kind of diaphragm can be formed with a small transfer cross section or diaphragm cross section, although the boreholes  49 ,  50  can be produced with relatively large diameters and thus with rough tools. 
         [0103]    For a construction that otherwise corresponds to  FIG. 7 , for the embodiment shown in  FIG. 8 , the extent of the hollow shaft  16  in the longitudinal direction lengthens in such a way that the hollow shaft projects into the groove  48 . A diaphragm for transfer of lubricant from the borehole  46  to the groove  48  is formed between a peripheral edge  54 , which is formed by the inner casing surface of the borehole  46  and also a transverse surface  55  defining the groove, and an edge  56 , which is formed by the outer casing surface  57  of the hollow shaft  16  and an end face  58  of the hollow shaft  16 . 
         [0104]    For a construction that otherwise corresponds to the embodiments described above, the camshaft  6  according to  FIG. 9  has no groove  48 . The boreholes  49 ,  50  and the transfer region  53  are also not provided for the embodiment according to  FIG. 9 , so that the lubricant is fed from the borehole  46  completely to the flow channel  51 . In the circular ring-shaped flow channel, which is formed in the borehole  46  and which has a rectangular half cross section and which is defined on the inside in the radial direction by the casing surface of the central screw  22  and also by an end face  58  of the hollow shaft  16 , there is a flow element  59 , which can involve a ring made from, for example, plastic or an elastomer, and covered by the central screw  22 . For the embodiment shown in  FIG. 9 , the flow element  59  has an approximately T-shaped half longitudinal section, wherein the transverse leg of the T contacts the casing surface of the central screw  22  under elastic pressure on the inside in the radial direction, while the vertical leg of the T extends outward in the radial direction and the end face of this leg forms a ring gap  60  with the borehole  46 , through which a diaphragm is created. 
         [0105]    In a deviating construction, the flow element  59  can be tensioned outward, for example, in the radial direction against the borehole  46 , wherein, in this case a ring gap  60  is formed between the inner surface of the flow element and the central screw. Also, a positive-fit holding of the flow element  59 , for example, in a suitable groove of the camshaft or the central screw, is conceivable. An arbitrary construction of the contours of the flow element  59  in the region of the ring gap  60  is possible for influencing the flow ratios, for example, with stepped transitions or continuous transitions. 
         [0106]    For the embodiment shown in  FIG. 10 , the hollow shaft  16  has in the region of the flow channel  51  a radial, peripheral groove  61 , which is defined on the side facing the chamfer  47  by a peripheral, radial projection  62  pointing inwardly in the radial direction. Between the projection  62  and the casing surface of the central screw  22 , a ring gap  63  is formed, which represents a diaphragm. The groove  61  forms a dead space  37  on the outside in the radial direction, because both the ring gap  63  and also the flow channel  51  open into the groove  61  on the inside in the radial direction from the dead space  37 . 
         [0107]    The camshaft  6  is supplied with a lubricant from a lubricant gallery of the cylinder head  8 . The transition of the lubricant from the engine-fixed cylinder head  8  to the rotating camshaft  6  is realized usually by known rotation transmitters. This typically involves a ring groove  64  of the outer casing surface of the camshaft  6 . The ring groove  64  is enclosed by a corresponding cylindrical casing surface  65  of the cylinder head  8 , to which a pass borehole  66  oriented in the axial direction toward the ring groove  64  leads out of the lubricant gallery. The pass borehole  66  can pass through the casing surface  65 , as shown in  FIG. 11 , in the radial direction or can pass through this surface, for example, tangentially. 
         [0108]    A rotation transmitter can be arranged in a radial bearing for the camshaft  6  or on a separate shoulder. For the latter, however, due to the usually larger radial gap, often sealing rings  67 ,  68 , for example, a steel sealing ring, cast-iron sealing ring, or plastic sealing ring, are required. In an arrangement of the rotation transmitter in a radial bearing of the camshaft  6  it is to be taken into account that the bearing width is reduced by the width of the ring groove. 
         [0109]    In another embodiment, ring grooves can be constructed fixed to the cylinder head, for example, in the bearing, the bearing bridge, or an installed bearing bushing. In the camshaft, no ring grooves  64  are required. 
         [0110]    The use of a rotation transmitter described above causes a continuous flow of lubricant from the cylinder head  8  into the camshaft  6  due to the peripheral ring groove and the radial boreholes  69 , which connect the ring groove  64  to the borehole  46 . 
         [0111]    For a special construction, the pass borehole  66  and the ring groove  64  are arranged offset relative to each other in the axial direction, by means of which, in the transfer of the lubricant from the pass borehole  66  to the ring groove  64 , a type of throttle is created, whose opening cross section becomes smaller the greater the offset in the axial direction between the pass borehole  66  and ring groove  64 . A throttle effect can also be achieved for a relatively large diameter of the pass borehole  66  and a large width of the ring groove  64 , so that no small boreholes or grooves, which are sensitive to contaminants and production, have to be created. 
         [0112]    According to another special construction, lubricant is fed via a cyclical lubricant supply. In such a case, the ring groove  64  is left out, so that a lubricant connection between the pass borehole  66  and the boreholes  69  is given only for rotational positions of the camshaft  6 , for which the boreholes  66 ,  69  align with each other or overlap. If increased transfer times are desired, then the transition region between the pass borehole  66  and borehole  69  of the cylinder head  8  or the casing surface of the camshaft  6  can have a groove running through a partial extent, so that a transfer from the pass borehole  66  to the borehole  69  is possible as long as these boreholes  66 ,  69  are connected to each other by the groove. In addition, by means of the construction of the width profile of the groove, there can be a variable transfer of the lubricant. Thus, a volume flow and mass flow of the lubricant can be given structurally and cyclically. Furthermore, a pulsing lubricant flow can be realized, which results in fluctuations in pressure that can be used, for example, for better mixing and wetting of the lubricating positions with the lubricant. Furthermore, through pulsing lubricant flows, the risk of blockages can be reduced, for example, for diaphragms or throttles. If such lubricant pulses lead to pulse oscillations in the lubricant cycle, then a non-return valve can be arranged in the lubricant circuit, in particular, in the region of the cylinder head  8 , in the region of the camshaft, and/or in the gear drive. 
         [0113]      FIG. 12  shows an embodiment, in which lubricant is fed via a radial blind borehole  70 , an axial, end-face blind borehole  71  of the camshaft opening into the blind borehole  70 , and a pass borehole  72  of the housing  9 . Assembly is simplified when a peripheral ring groove  73  is provided in the transition region between the boreholes  71  of the camshaft and the boreholes  72  of the housing  9 , such that, during assembly, the boreholes  71 ,  72  do not have to be aligned coaxial to each other. 
         [0114]      FIG. 13  shows an embodiment, which corresponds essentially to the embodiment according to  FIG. 9 , wherein, however, no flow element  59  is provided. 
         [0115]      FIG. 14  shows an embodiment, in which the ring groove  64  is connected directly to the ring channel  73  via a borehole  74  inclined relative to the longitudinal axis  21 - 21  and the transverse axis. 
         [0116]    For the embodiment shown in  FIG. 15 , the direct connection of the ring channel  73  and the ring groove  64  is realized via a borehole  75 , which is formed on the end face in the camshaft and which opens into the ring groove  64  and which is drilled through the ring channel  73 . 
         [0117]    In addition to the structural measures for constructing the flow cross sections in the cylinder head and also in the camshaft, the flow ratios in the lubricant circuit in the gear drive can be influenced. Here, the supply borehole can be throttled through the use of a throttle or diaphragm. Alternatively or additionally, the throttling of the discharge through a rear-side closing of the gear drive, for example, with a sheet-metal cover, is possible, which forms, together with the adjustment shaft, a ring-shaped gap, in particular, with a gap height in the range from 0.1 to 2 mm. 
         [0118]    In addition, it is possible to use bearings in the gear drive, which are equipped with sealing elements. According to  FIG. 16 , a ring channel between the hollow shaft  16  and central screw  22  has a ring width in the range from 0.2 to 1 mm. The radial connection boreholes between this flow channel and the inner space of the gear drive advantageously have a diameter between 0.5 and 3 mm. Additional influences or throttles or diaphragms can be realized by setting the axial and/or radial gaps  76 , which can be set structurally and which form flow cross sections or diaphragms or throttles for the lubricant. 
         [0119]    According to another construction of a camshaft adjuster  1 , the outer casing surface of the housing  9  has recesses or windows  77 , which can be distributed uniformly or non-uniformly in the peripheral direction, cf.  FIG. 17 . 
         [0120]      FIG. 18  shows additional options for the arrangement of recesses or openings  78  in the region of one end face of the camshaft adjuster  1 . A transmission of the lubricant via the camshaft can be eliminated if a lubricant is fed through the openings  78 ,  77  to the gear drive  2 . For example, the lubricant can be fed via a lubricant injector through the openings  77 ,  78 . Such a lubricant injector can be fixed to the cylinder head or arranged on a timing case. In the simplest case, a lubricant injector can involve only one lubricant borehole, from which a fine lubricant stream is discharged and which occurs at a point outside of the gear drive or within the gear drive, for example, through the openings  77 ,  78 . In particular, such a point can lie as close as possible to the rotational axis in the interior of the gear drive. Due to the centrifugal force acting on the lubricant in the rotating system, the lubricant is distributed outward to the lubricating positions, for example, to a bearing and/or to the toothed section. 
         [0121]    In addition, through the arrangement of the openings  77 ,  78  of the gear housing, the lubricant can be sprayed directly onto a toothed section or other lubricating positions. It is also conceivable that the spraying with lubricant is combined with the lubricant supply of other engine components, for example, a chain or a tensioner. It is also conceivable that a point or a surface outside of the gear drive  2  is sprayed with the lubricant. Lubrication is then guaranteed through the rebounding or reflected lubricant or a lubricant mist generated in this way. 
         [0122]    According to an alternative construction, a lubricant supply can be realized by means of the lubricant mist, which is already present in a timing case and which can penetrate into the camshaft adjuster through the openings  77 ,  78 . 
         [0123]    In another construction of a lubricant supply according to  FIG. 20 , outside of the gear drive there is a drop plate  80 , on which the lubricant mist condenses and drips. Alternatively or additionally, special drop lubricant nozzles can be provided, which are oriented selectively in the direction of the openings  77 ,  78 . 
         [0124]    To reliably guarantee functioning for lubrication with a lubricant mist, mist lubricant droplets, or with a lubricant stream, even at low temperatures of the lubricant or for a cold start, the lubricating positions, for example, slide bearings and/or toothed sections, are to be equipped with emergency-running properties. Such emergency-running properties can be guaranteed, for example 
         [0125]    by a coating of the functional partners or 
         [0126]    by forming lubricant reservoirs. 
         [0127]    In particular, the lubricant reservoirs are provided by microscopically or macroscopically small pockets of the lubricating positions, in which lubricant can be stored for a cold start or for low lubricant temperatures. Better emergency-running properties can also be provided, advantageously, when roller bearings are provided at the bearing positions as much as possible. 
         [0128]    Furthermore, for lubrication, oil dripping from an oiled traction element (timing chain) can also be used, which passed through an opening of the housing. Under some circumstances, the traction element is lubricated by wobble or spray oiling or by stripping oil from oiled chain tensioners or deflection rails. A part of the oil supplied by the chain can drop above the drive wheel (chain wheel) of the gear drive and can thus be led into openings of the gear drive lying underneath. In addition, it is possible to feed oil through the capillary effect to the gear drive or to drip positions lying above the gear drive. It is also possible that oil is “blown,” for all practical purposes, to the lubricating position, by air currents resulting, e.g., from the drive movement of the control drive or adjustment parts. 
       LIST OF REFERENCE SYMBOLS 
       [0000]    
       
           1  Camshaft adjuster 
           2  Gear drive 
           3  Drive wheel 
           4  Adjustment shaft 
           5  Driven shaft 
           6  Camshaft 
           7  Electric motor 
           8  Cylinder head 
           9  Housing 
           10  Sealing element 
           11  Sealing element 
           12  Coupling 
           13  Eccentric shaft 
           14  Bearing element 
           15  Wobble plate 
           16  Hollow shaft 
           17  Bearing element 
           18  Driven conical gear wheel 
           19  Bearing 
           20  Drive conical gear wheel 
           21  Longitudinal axis 
           22  Central screw 
           23  Lubricating position 
           24  Lubricating position 
           25  Feed recess 
           26  Flow channel 
           27  Flow channel 
           28  Casing surface 
           29  Casing surface 
           30  Borehole 
           31  Reservoir 
           32  Pump 
           33  Filter 
           34  Outlet opening 
           35  Filter element 
           36  Inner space 
           37  Dead space 
           38  Wall 
           39  Outlet opening 
           40  Outlet opening 
           41  Diaphragm 
           42  Throttle 
           43  Diaphragm 
           44  Throttle 
           45  Borehole 
           46  Blind borehole 
           47  Chamfer 
           48  Groove 
           49  Borehole 
           50  Borehole 
           51  Flow channel 
           52  Borehole 
           53  Transfer region 
           54  Edge 
           55  Transverse surface 
           56  Edge 
           57  Casing surface 
           58  End face 
           59  Flow element 
           60  Ring gap 
           61  Groove 
           62  Projection 
           63  Ring gap 
           64  Ring gap 
           65  Casing surface 
           66  Pass borehole 
           67  Sealing ring 
           68  Sealing ring 
           69  Borehole 
           70  Blind borehole 
           71  Blind borehole 
           72  Pass borehole 
           73  Ring channel 
           74  Borehole 
           75  Borehole 
           76  Gap 
           77  Opening 
           78  Opening 
           79  End face 
           80  Drop plate 
           81  Intermediate space 
           82  Sub-region 
           83  Sub-region 
           84  Flow channel 
           87  Flow channel region 
           86  Outlet opening 
           85  Inlet opening