Abstract:
An electromotive camshaft adjuster for adjusting the angle of rotation of the camshaft ( 14 ) of an internal combustion engine relative to the crankshaft thereof is provided. The camshaft adjuster includes a triple-shaft gear mechanism, which has a driving wheel ( 2, 2   a ′) that is fixed to the crankshaft and is embodied as a sprocket or a synchronous belt wheel, an output part which is fixed to the camshaft, and an adjustment shaft ( 18, 18′ ) which is connected in a rotationally fixed manner to a rotor of an electric adjustment motor, having a stator that is fixed on the internal combustion engine. In order to keep the effort for producing the adjusting gears relatively low, the triple-shaft gear mechanism is preferably constructed as a swashplate or single eccentric internal gear drive ( 1, 25 ), the effort for production thereof being minimized by forming the same in a non-cutting manner, reducing the number of components, and inexpensively adjusting or compensating the backlash.

Description:
BACKGROUND 
   The invention relates to an electromotive camshaft adjuster for adjusting the angle of rotation of the camshaft of an internal combustion engine relative to the crankshaft thereof. 
   Electromotive camshaft adjusters are distinguished by quick and exact camshaft adjustment for the entire operating range of the internal combustion engine. This also applies for a cold start and a restart of the internal combustion engine after stalling. 
   Electrical camshaft adjusters are comprised of an adjustment mechanism connected in a rotationally fixed manner to the camshaft and an electromotive adjusting drive, which is fixed to the adjusting shaft and whose motor shaft attaches to the adjusting shaft of the adjusting mechanism rotating at the camshaft rotational speed. 
   For the most part, the following triple-shaft gear mechanisms are used as the adjustment mechanism: 
   Swashplate (or Wobbleplate) Drive. 
   These drives have a simple construction. Their ability to be manufactured in mass production, however, has not been clarified. In addition, they are susceptible to tolerances, and the manufacture of the teeth parts is associated with high costs, because these parts have to be manufactured with cutting methods due to high loading and for reasons of accuracy. 
   Double Eccentric Internal Gear Drive. 
   This type of drive is very functional and quiet running, but generates considerable costs due to the number of components. 
   Planetary and Cycloid Gears (So-Called Harmonic Drive Gears). 
   The latter is described in DE 40 227 35 A1, in which an electromotive camshaft adjuster for adjusting the angle of rotation of an internal combustion engine relative to the crankshaft thereof is disclosed, with a triple-shaft transmission, which has a crankshaft-fixed drive wheel constructed as a sprocket or synchronous belt wheel and a camshaft-fixed driven part and also an adjusting shaft, which is connected in a rotationally fixed manner to the rotor of an electric adjustment motor and whose stator is fixed to the internal combustion engine. 
   This cycloid gear drive is distinguished by low installation space and high function reliability, but requires a large construction expense. 
   The invention is based on the objective of constructing a triple-shaft gear mechanism for an electromotively driven camshaft adjuster, which provides a relatively low manufacturing expense. 
   SUMMARY 
   The objective is met by a device according to the invention. 
   The swashplate drive and the single eccentric internal gears offer various possibilities for reducing manufacturing costs. Both types of drives can be produced largely without cutting. The swashplate drive also offers the possibility of simple tooth backlash compensation, while the single eccentric internal gears offers many possibilities for reducing the number of components. 
   It is advantageous that brushless DC motors are provided as electric adjustment motors, especially motors with rare-earth magnets and with bipolar operation. These motors are distinguished through simple construction, high acceleration, and practically wear-free operation due to the lack of a commutator. 
   The first and second conical gear wheel and also the swashplate of the swashplate drive with teeth on both sides is suitable preferably for powder metallurgical production. The strength and hardness of these components can be increased after sintering, for example, through temper rolling of the teeth or hot pressing or high-pressure pressing without negatively affecting the accuracy of the parts. The components listed above can also be made from a steel blank through wobble pressing or axial rolling. 
   An important feature for the quality of the adjustment drive is the correct circumferential backlash of the teeth pairs. Through the dynamic camshaft torque, backlash that is too large can lead to rotational vibrations between the two conical gear wheels during operation. Therefore, noise or control problems can be produced. If the backlash is too small, the adjustment gear will jam or its efficiency will be too poor. However, backlash cannot be avoided. The magnitude of backlash is influenced by the quality of the teeth in the swashplate and the conical gear wheels and also by the dimensional tolerances of the gear wheel pairs that determine the axial distance and the alignment. 
   Limiting the dimensional tolerances to their permissible highest value through high manufacturing accuracy is successful only to a limited extent. For this reason, it is important to make the backlash adjustable. The backlash compensation ensures that the minimum circumferential backlash is produced when reaching the top tolerance limits of the dimensional tolerances of the components. If the dimensions of the components reach the lower tolerance limits or between the lower and upper tolerance limits, theoretically a profile cutting of the teeth is performed. The backlash is then corrected by a plain washer coupled between the first conical gear wheel and the housing. 
   Alternatively, the teeth can be biased by springs between the sprocket wheel drive and the camshaft driven part and/or the adjustment drive, in order to prevent backlash-dependent noise generation. The difficulty of this method lies in maintaining an optimum biasing, which combines low noise generation with high gear efficiency. 
   An eccentric internal gear drive, which is constructed as a single eccentric internal gear, offers cost advantages in that it has only one internal eccentric for first and second spur gears, which are connected to each other in a rotationally fixed manner and which roll on first and second ring gears. Here, the first spur gear and ring gear are used exclusively for conversion in the phase adjustment and the second spur gear and ring gear are used also or even exclusively as coupling teeth for passing the drive and adjustment power to the camshaft. 
   The second spur gear here completes the same eccentric motion as the first, because both are connected to each other in a rotationally fixed manner. If the second ring gear/spur gear pair has the same difference in tooth number as the first, it is used only as tooth coupling that does not contribute to the overall modulation of the adjustment gear. However, it is also possible to distribute the overall modulation onto both gear wheel pairs, which gives greater freedom in selecting the teeth. 
   In principle, like in double eccentric internal gear mechanisms, a claw, segment, or pin coupling, which takes over the coupling function, is also conceivable instead of the tooth coupling. The single eccentric internal gear mechanism then has an even simpler shape, but the pins or claws must slide on their counter surface for compensating for the eccentric motion. Therefore, a lower efficiency than with a tooth coupling is necessary, in which the second spur gear rolls in the second ring gear with low friction. 
   For further reducing the friction, the single internal eccentric and the two spur gears and optionally the drive wheel are roller supported, wherein the latter preferably has a four-point support. The roller bearing can be a ball bearing, cylinder bearing, or needle bearing. A four-point bearing is suitable especially for absorbing tilting moments, like those that can appear in a drive wheel. If the bearing friction has a small role relative to construction costs and installation space, then all of the roller bearings can be replaced by sliding bearings for a correspondingly dimensioned drive of the adjustment shaft. 
   Lower production costs are also achieved by constructing the ring gears and spur gears as annular gears with internal and external teeth, respectively, which are cut into the necessary length by tubes with internal and external profiling, respectively. The profiled tubes can be drawn or extruded or sintered, for example. 
   Another way to reduce costs is to form the hollow and spur gears made from bands profiled with teeth into annular gears, which are closed by welding or clips and then recalibrated. 
   Production costs can also be reduced by expanding the first spur gear by the width of the second spur gear and by meshing the first spur gear with two ring gears with equal teeth. 
   Backlash compensation is performed separately for the two spur gear/ring gear pairs in the single eccentric internal gear, with the backlash compensation being performed in the first spur gear/ring gear pair by selecting a matching eccentric and in the second spur gear/ring gear pair by a correspondingly profile-shifted second spur gear/ring gear or by an additional compensating eccentric that can be adjusted independent of the first eccentric and that is locked in rotation on the adjustment shaft. An especially economical form of the backlash compensation is provided in performing this compensation through slightly conically shaped spur gears and ring gears pushed axially one inside the other up to shortly before linear contact, preferably using its manufacturing-specific conical form. 
   A more economical way for achieving optimum backlash is provided by a run-in operation of the adjustment gear with a wear layer made from, for example, copper or plastic, which runs in under biasing until reaching a given backlash, which is relatively soft and allows sliding, and which is applied to its teeth. 
   Instead of through backlash compensation, the tooth noise can also be reduced through helical spur gears and ring gears. Through an opposite pitch of the teeth of the two spur gears and ring gears, their axial forces are canceled out, whereby the bearing is simplified. 
   Similarly for a swashplate drive, for a single eccentric internal gear, a spring biasing of the teeth between the camshaft driven part and the driving wheel and/or the adjustment drive is also possible for reducing the tooth noise. 
   A construction of the invention that is favorable to production is provided in that the second ring gear can be constructed in one piece with the driven flange and optionally with the intermediate piece and can be produced through, for example, wobble or axial pressing, sintering, or deep drawing. In this way, the number of components can be considerably reduced. 
   There are advantages in terms of production if the eccentric and the adjustment shaft can be constructed in one or two pieces with the tooth coupling. The one-piece construction offers the advantage of a smaller number of components. It can be realized by sintering, wobble pressing, and deep drawing. The two-part construction offers the advantage that the eccentric can be produced economically from an eccentric tube, in which a tooth coupling plate can be pressed. 
   A simple construction, low friction, and freedom of play are achieved in that the single eccentric internal gear has a so-called ball orbital coupling instead of a ring gear/spur gear pair transmitting the camshaft torque, in which balls are guided on each half in circuit tracks of two equal steel plates biased axially and balance the eccentric motion. One steel plate is connected in a rotationally fixed manner to a spur gear and the other steel plate is connected to a camshaft-fixed part. 
   A single eccentric internal drive with small axial length is achieved in that a driving wheel and a driven part, a first and a second ring gear, and also a first and a second spur gear are arranged coaxial, wherein the driving wheel is connected in a rotationally fixed manner to the first ring gear, the first spur gear is connected in a rotationally fixed manner through a flange to the second ring gear, and also the second spur gear is connected in a rotationally fixed manner to the driven part and the first ring gear meshes with the first spur gear and the second ring gear meshes with the second spur gear. 
   For certain applications, it can be advantageous that in a single eccentric internal gear, the second ring gear is constructed as a second spur gear and the second spur gear is constructed as a second ring gear, wherein the second ring gear and the second spur gear mutually engage each other. 
   It is also conceivable that the spur gears and ring gears of the single eccentric internal gear are replaced by corresponding friction wheels. These are distinguished through low noise and resistance to wear, but require sufficient contact force. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Additional features of the invention will be understood from the following description and the drawings, in which an embodiment of the invention is shown schematically. Shown are: 
       FIG. 1  a longitudinal section view through a swashplate drive; 
       FIG. 2  a longitudinal section view through a single eccentric internal gear drive; 
       FIG. 3  a view of the single eccentric internal gear drive from  FIG. 2 ; 
       FIGS. 4 to 7  longitudinal section views through structural variants of the single eccentric internal gear drive of  FIG. 2 ; 
       FIG. 8  a cross sectional view through the single eccentric internal gear from  FIG. 4 , but with a one-piece construction of the second ring gear, the drive flange, and the intermediate piece; 
       FIG. 9  a side view of a ball orbital coupling; 
       FIG. 10  a perspective view of a plate of the ball orbital coupling from  FIG. 9 ; 
       FIG. 11  a cross sectional view through a single eccentric internal gear drive with coaxial arrangement of gear wheels; 
       FIG. 12  a cross sectional view through a single eccentric internal gear drive according to  FIG. 11 , but with interchanged second ring gear and spur gear. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In  FIG. 1  a longitudinal section through a swashplate drive  1  is shown. This has a driving wheel  2  constructed as a sprocket pinion. This driving wheel is connected in a rotationally fixed manner to a crankshaft of an internal combustion engine via a sprocket (not shown) and is constructed in one piece with a rotationally symmetric gear housing  3 . 
   The gear housing  3  has on its free end an outer flange  4  with threaded bores  5 , on which a first conical gear wheel  6  is connected by means of screws  7 . On the driving wheel-side end of the gear housing  3  there is an inner flange  8 , which is used for radial and axial support or position fixing of the gear housing  3  and the driving wheel  2 . The radial support of the housing takes place on a step  9  of a second conical gear wheel  10 , while its axial position fixing is realized by a shoulder  11  of the housing in connection with a stopping plate  12 , which is pressed and/or welded to the driving wheel  2 . 
   The second conical gear wheel  10  is connected in a rotationally fixed manner to a camshaft  14  by a central tension screw  13 . A hollow flange  15  on the free end of the camshaft  14  is used for the axial and radial position fixing of the second conical gear wheel  10  and the stopping plate  12 . 
   Between the conical gear wheels  6 ,  10  there is an inclined swashplate  16  with teeth on both sides. The inclination of the swashplate  16  is selected so that the teeth of each side are continuously engaged with one of the two conical gear wheels  6 ,  10 . The swashplate  16  is supported by two deep groove ball bearings  17  constructed as fixed bearings on an adjustment shaft  18 , which is supported, in turn, on a cylindrical part  20  of the second conical gear wheel  10  with two needle bearings  19  constructed as movable bearings. 
   The adjustment shaft  18  is connected in a rotationally fixed manner to a not-shown rotor of a brushless, reversible DC motor. 
   The two conical gear wheels  6 ,  10  and the swashplate  16  are fabricated using powder metallurgy. Their teeth are post-treated for increasing the strength for constant spacing accuracy through, for example, temper rolling of the teeth or hot or high-pressure pressing. 
   The swashplate gear  1  is fed via oil lines  21 , which start from a camshaft bearing  22  and lead up to an annular space  23  and further through a not-shown, radial bore to the bearings  19  and  17  and also to the teeth. A corresponding shape of the first conical gear wheel  6  guarantees a sufficient oil level in the swashplate gear  1 . 
   The backlash can be adjusted easily in the swashplate gear  1 . Through a fitting shim  24 , which can be placed between the outer flange  4  of the gear housing  3  and the first conical gear wheel  6 , the backlash is set to zero. By replacing this shim by one of increased thickness, the backlash is adjusted. 
   The swashplate drive  1  functions in the following way: 
   In regular operation, that is, at constant phase position, the swashplate drive  1  including the rotor of the not-shown electric adjustment motor turns as a whole at the camshaft rotational speed. For adjusting the control times for a retarded or advanced position, the adjustment motor accelerates or decelerates its rotor relative to the camshaft  14 . In this way, the adjustment shaft  18  turns in front of or behind relative to the gear housing  3 , whereby the swashplate  16  rolls on the conical gear wheels  6 ,  10  according to the low difference in tooth number between the swashplate and the conical gear wheels with large modulation and completes the phase adjustment. 
     FIG. 2  shows a longitudinal section through a single eccentric internal gear drive  25  and  FIG. 3  shows a view of the driven side of this gear drive. 
   In the longitudinal section of  FIG. 2 , a driving wheel  2   a  constructed as a sprocket wheel is to be seen, which is connected in a rotationally fixed manner to a first ring gear  26 . This connection can be achieved through pressing, especially after knurling and/or through laser welding. 
   The first ring gear  26  meshes with a first spur gear  27 , which is connected in a rotationally fixed manner to a second spur gear  28  through an interference fit. This is supported by a first needle bearing  29  on a single internal eccentric  30 , which is in rotationally fixed connection with a not-shown rotor of an electric adjustment motor via a tooth coupling  31 . The internal eccentric  30  is supported by a second needle bearing  32  on an intermediate piece  33 , which can be tensioned in a rotationally fixed manner by a not-shown central tension screw to the similarly not-shown camshaft via a driven flange  34 . The second spur gear  28  meshes with a second ring gear  35 , on whose periphery the first ring gear  26  is supported with the driving wheel  2   a  in a sliding manner. 
   The second ring gear  35  is connected in a rotationally fixed manner to the camshaft-fixed driven flange  34 . Both contact a stop plate  36  axially, which is connected in a rotationally fixed manner to the first ring gear  26 . 
   The driven flange  34  has a tab  37 , which can pivot in an annular section  38  of the stop plate  36  defining the adjustment region of the single eccentric internal gear drive  25  between two stops  39 ,  40 , as also emerges from  FIG. 3 . The driven flange  34  can be produced without cutting through sintering, wobble pressing, or axial rolling. It can also be sintered together with the second ring gear  35 . 
   A sheet-metal cover  41 , which is pressed into a recess  42  and which limits the axial movement of the two spur gears  27 ,  28  and an adjustment shaft  18 ′, is provided on the adjustment motor side of the single eccentric internal gear drive  25 . 
   The single eccentric internal gear drive  25  functions as follows: 
   In regular operation, the single eccentric internal gear drive  25  and the rotor of the adjustment motor rotate as a whole at the camshaft rotational speed. When the camshaft is adjusted to a retarded or advanced position, the adjustment motor accelerates or decelerates the adjustment shaft  18 ′ with the internal eccentric  30 . In this way, the spur gears  27 ,  28  roll on the ring gears  26 ,  35  and produce the phase adjustment with large modulation due to the low difference in tooth number of the associated spur gears/ring gears. 
     FIG. 4  represents a single eccentric internal gear drive  25 ′ as a structural variant of the single eccentric internal gear  25  of  FIG. 2 . One driving wheel  2   a ′ is sintered together with a first ring gear  26 ′ and its teeth in one piece. If necessary, the teeth can be temper rolled, in order to achieve increased tooth strength. 
   A second ring gear  35 ′ is connected to a driven flange  34 ′ by an interference fit and by welding. Both components can be produced advantageously also in one piece through sintering. 
   A first spur gear  27 ′ is expanded by the width of a second spur gear  28 ′. The teeth of the ring gears  26 ′,  35 ′ have a constant internal diameter thanks to the profile shift despite different tooth numbers and thus makes it possible to mesh with the first spur gear  27 ′. The first spur gear  27 ′ can be produced through sintering but also through wobble pressing, cold pressing, or extrusion. 
   The first spur gear  27 ′ is supported by means of a first needle bearing  29 ′ on a single internal eccentric  30 ′ and this is supported by means of a second needle bearing  32 ′ on an intermediate piece  33 ′. This can be produced through, among other things, sintering, extrusion, or deep drawing. Its reduced outer and inner diameter relative to the intermediate piece  33  makes contact of the screw head of the central tensioning screw necessary on an end surface  43  of the intermediate piece  33 ′. This results in the modified form of an adjustment shaft  18 ″. This same can be produced through extrusion or deep drawing and a teeth coupling  31 ′ through stamping. 
   The sheet-metal cover  41 ′ is also used in this variant as an axial stop for the first spur gear  27 ′ and the adjustment shaft  18 ″ and also as a lubricating oil guide. A snap ring  44  is used as an axial stop for the second ring gear  35 ′ on the driven side. 
   The single eccentric internal gear drive  25 ″ shown in  FIG. 5  differs from the single eccentric internal gear drives  25  or  25 ′ by the attachment of a stop plate  36 ′ on the first ring gear  26 ″. This is performed tangentially by pegs  46  of the stop plate  36 ′ projecting into slots  45  of this wheel, while a snap ring  44 ′ is used as an axial retainer. 
   Another difference lies in a two-part single internal eccentric  30 ″, which can be cut from a correspondingly shaped, extruded tube and which can be pressed and welded with a stamped tooth coupling  31 ″. 
   In a sintered driven flange  34 ″, a radial lubricating oil channel  47  is engraved, which provides the needle bearing  32 ″,  29 ″ and the teeth of the spur gears and ring gears  27 ″,  28 ″,  26 ″,  35 ″ with lubricating oil. The two spur gears  27 ″,  28 ″ are sintered in one piece, including their teeth. 
   The single eccentric internal gear drive  25 ′″ according to  FIG. 6  is distinguished from the preceding variants through the following features: 
   A one-piece driving wheel  2   a ″/first ring gear  26 ′″ is suitable as a wobble pressed part due to its dimensions; 
   A deep-drawn stop plate  36 ″ is connected in a rotationally fixed manner to the driving wheel  2   a ″ by an interference seat and laser welding. It is used with its inner periphery as a sliding bearing for the driving wheel  2   a ″ and for the first ring gear  26 ′″ and also as an axial stop for a second ring gear  35 ′″ and the driven flange  34 ′″ connected to it. 
   The single eccentric internal gear drive  25 ″″ shown in  FIG. 7  is distinguished by a first spur gear and ring gear  27 ″″,  26 ″″ with a rectangular cross section. These rings are suitable especially for extending a corresponding internal or external geared tube. The same applies for the first spur gear  27  of  FIG. 2  and the first spur gear  27 ′″ of  FIG. 6 . 
   The first ring gear  26 ′″ is pressed into the driving wheel  2   a ′″, while a second ring gear  35 ′″ is supported in the driving wheel  2   a ′″ in a sliding way and guided axially by a stop plate  36 ′″ welded to the same. 
   In  FIG. 8 , the single eccentric internal gear drive  25 ′ from  FIG. 4  is shown in cross section, but with a one-piece construction of the intermediate piece  33 ′ with the driving flange  34 ′ and the ring gear  35 ′. Therefore, the number of components is reduced significantly. Sintering is the main process considered for production. 
     FIG. 9  shows a side view of a so-called ball orbital coupling  49 , which is used as a replacement for a ring gear/spur gear tooth coupling for compensating the eccentric motion similar to a claw, segment, or pin coupling. The ball orbital coupling  49  has two steel plates  50 , between which balls  51  are jammed under axial biasing. The balls  51  are guided on each half in circuit tracks  52  of the steel plates  50  (see also  FIG. 10 ), where they execute a circular motion, without requiring play. One of the steel plates  50  is connected in a rotationally fixed manner to one of the spur gears of the single eccentric internal gear drive and the other is connected to a camshaft-fixed part of the gear. 
     FIG. 11  represents a single eccentric internal gear drive  25 ′″″, which is connected in a rotationally fixed manner to a camshaft (not shown) via an elastomer coupling  48 . The special characteristic of this gear is the coaxial arrangement of a first and second ring gear  26 ′″″,  35 ′″″ and a first and second spur gear  27 ′″″,  28 ′″. In this way, relatively little axial space is required. In addition, the spacing of the first ring gear  26 ′″″ to a double deep groove ball bearing  53 , which receives the tilting moment of this wheel and the load of a driving wheel  2   a ″″, is relatively small. This has a positive effect on the rolling behavior of the teeth due to the smaller radial shifting. The driving wheel  2   a ″″ is constructed in one piece with the first ring gear  26 ′″″. The first spur gear  27 ′″″ and the second ring gear  35 ′″″, which are connected to each other by a flange  54 , are constructed in the same way. The second spur gear  28 ′″ is constructed in one piece with a driven part  55  and an adjustment shaft  18 ″″ with a single internal eccentric  30 ′″. The single internal eccentric  30 ′″ and the first spur gear  27 ′″″ with the second ring gear  35 ′″″ are supported on a second and third double deep groove ball bearing  56 ,  57 . 
   In  FIG. 12 , the cross section of a single eccentric internal gear drive  25 ″″″ is shown, which differs from that of  FIG. 11  through the interchanging of the second ring gear and the second spur gear. These are constructed in  FIG. 12  as a new second ring gear  35 ″″″ and a new second spur gear  28 ″″ and mutually engage each other. A driving wheel  2   a ″″″, a flange  54 ′, and a driven part  55 ″ are adapted to the modified construction. The function of the single eccentric internal gear drive  25 ′″″ and  25 ″″″ corresponds to the gear drive shown in  FIGS. 2 to 8 . 
   
     
       
             
           
             
             
             
           
         
             
                 
             
             
               List of reference symbols 
             
             
                 
             
           
           
             
                 
             
           
        
         
             
                 
                1 
               Swashplate drive 
             
             
                 
                2, 2a, 2a′, 2a′′, 2a′′′, 2a′′′′, 2a′′′′′ 
               Driving wheel 
             
             
                 
                3 
               Gear housing 
             
             
                 
                4 
               Outer flange 
             
             
                 
                5 
               Threaded bore 
             
             
                 
                6 
               First conical gear wheel 
             
             
                 
                7 
               Screw 
             
             
                 
                8 
               Inner flange 
             
             
                 
                9 
               Step 
             
             
                 
               10 
               Second conical gear wheel 
             
             
                 
               11 
               Shoulder 
             
             
                 
               12 
               Stop plate 
             
             
                 
               13, 13′ 
               Central tensioning screw 
             
             
                 
               14 
               Camshaft 
             
             
                 
               15 
               Hollow flange 
             
             
                 
               16 
               Swashplate 
             
             
                 
               17 
               Deep groove ball bearing 
             
             
                 
               18, 18′, 18′′, 18′′′, 18′′′′ 
               Adjustment shaft 
             
             
                 
               19 
               Needle bearing 
             
             
                 
               20 
               Cylindrical part 
             
             
                 
               21 
               Oil line 
             
             
                 
               22 
               Camshaft bearing 
             
             
                 
               23 
               Annular space 
             
             
                 
               24 
               Shim 
             
             
                 
               25, 25′, 25′′, 25′′′, 25′′′′, 25′′′′′, 25′′′′′′ 
               Single eccentric internal 
             
             
                 
                 
               gear drive 
             
             
                 
               26, 26′, 26′′, 26′′′, 26′′′′, 26′′′′′ 
               First ring gear 
             
             
                 
               27, 27′, 27′′, 27′′′, 27′′′′, 27′′′′′ 
               First spur gear 
             
             
                 
               28, 28′, 28′′, 28′′′, 28′′′′ 
               Second spur gear 
             
             
                 
               29, 29′, 29′′ 
               First needle bearing 
             
             
                 
               30, 30′, 30′′, 30′′′ 
               Single internal eccentric 
             
             
                 
               31, 31′, 31′′ 
               External spline coupling 
             
             
                 
               32, 32′, 32′′ 
               Second needle bearing 
             
             
                 
               33, 33′ 
               Intermediate piece 
             
             
                 
               34, 34′, 34′′, 34′′′ 
               Driven flange 
             
             
                 
               35, 35′, 35′′, 35′′′, 35′′′′, 35′′′′′, 35′′′′′′ 
               Second ring gear 
             
             
                 
               36, 36′, 36′′, 36′′′ 
               Stop plate 
             
             
                 
               37 
               Tab 
             
             
                 
               38 
               Ring section 
             
             
                 
               39 
               First stop 
             
             
                 
               40 
               Second stop 
             
             
                 
               41, 41′ 
               Sheet-metal cover 
             
             
                 
               42 
               Recess 
             
             
                 
               43 
               End surface 
             
             
                 
               44, 44′ 
               Snap ring 
             
             
                 
               45 
               Slot 
             
             
                 
               46 
               Peg 
             
             
                 
               47 
               Lubricating oil channel 
             
             
                 
               48 
               Elastomer coupling 
             
             
                 
               49 
               Ball orbital coupling 
             
             
                 
               50 
               Steel plate 
             
             
                 
               51 
               Ball 
             
             
                 
               52 
               Circuit track 
             
             
                 
               53 
               First double deep groove 
             
             
                 
                 
               ball bearing 
             
             
                 
               54, 54′ 
               Flange 
             
             
                 
               55, 55′ 
               Driven part 
             
             
                 
               56 
               Second double deep groove 
             
             
                 
                 
               ball bearing 
             
             
                 
               57 
               Third double deep groove 
             
             
                 
                 
               ball bearing 
             
             
                 
               58 
               Third spur gear