Abstract:
A camshaft adjusting device for internal combustion engines of motor vehicles has an intake camshaft adjuster and an exhaust camshaft adjuster driven by an endless drive connected to the crankshaft. The intake and exhaust camshaft adjusters are connected by a gear transmission to one another. The intake and exhaust camshaft adjusters each have a gear forming a part of the gear transmission. The intake and exhaust camshaft adjusters are directly drivingly connected by the gears or a common gear wheel fixedly connected to an intermediate shaft is positioned between the gears.

Description:
BACKGROUND OF INVENTION 
     1. Field of the Invention 
     The invention relates to a camshaft adjusting device for internal combustion engines of motor vehicles, comprising an intake camshaft adjuster and/or an exhaust camshaft adjuster drivingly connected to a crankshaft that drives by means of an endless drive the camshaft adjusting device. 
     2. Description of the Related Art 
     Camshaft adjusting devices are provided in order to control in internal combustion engines of motor vehicles the opening time of the intake valves as a function of the momentary power demand of the internal combustion engine. For this purpose, an intake camshaft adjuster  1  ( FIG. 2 ) and/or an exhaust camshaft adjuster  2  are provided that are drivingly connected by means of an endless circulating chain  5  to a crankshaft  3 . The camshaft adjusters  1 ,  2  each comprise a stator in which a rotor, fixedly mounted on the camshaft  12 ,  29 , respectively, is arranged rotatably relative to the stator. The rotors are loaded by a pressure medium when they are to be rotated relative to the stator. The stators of the two camshaft adjusters  1 ,  2  each are provided with a drive wheel  6 ,  6 ′ across which the chain  5  is guided. In the case of cramped or tight mounting space, it is difficult and sometimes not possible to mount the chain  5 . 
     SUMMARY OF INVENTION 
     It is an object of the present invention to configure the camshaft adjusting device of the aforementioned kind such that it can be simply mounted even in the case of cramped mounting conditions. 
     In accordance with the present invention, this is achieved in that the two camshaft adjusters engage one another by means of a gear transmission. 
     In the camshaft adjusting device of the present invention the two camshaft adjusters are drivingly connected to one another by means of a gear transmission. The drive wheel of the first camshaft adjuster can be mounted easily in a precise position wherein, even in the case of cramped mounting conditions, the endless circulating drive element can be mounted easily. 
     The two camshaft adjusters each have a stator surrounding a rotor that is rotatable relative to the stator and is fixedly mounted on its camshaft, respectively. The rotors of the camshaft adjusters can be adjusted by pressure medium in the desired direction relative to the stator in order to change in this way the opening time of the intake valves of the internal combustion engine. 
     In a first embodiment of the invention, the camshaft adjusters directly engage one another by means of their gears. In this case, the crankshaft is connected by means of the endless drive only to the first camshaft adjuster. 
     In a second configuration, the gears of the two camshaft adjusters engage a common gear wheel which is mounted fixedly on an intermediate shaft. The intermediate shaft is drivingly connected by means of the endless drive to the crankshaft. In this case, the intermediate shaft is rotatably driven by means of the endless drive so that the camshaft adjusters are driven via the gear transmission. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  shows a first embodiment of a camshaft adjusting device with camshaft adjusters according to the invention. 
         FIG. 2  shows a camshaft adjusting device according to the prior art. 
         FIG. 3  is an exploded view of the camshaft adjusting device according to the present invention. 
         FIG. 4  is a perspective illustration showing a rearview of the camshaft adjusting device according to the invention. 
         FIG. 5  is a perspective illustration of a front view of the camshaft adjusting device according to the invention. 
         FIG. 6  is a schematic illustration of a second embodiment of a camshaft adjusting device according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The camshaft adjusting device according to  FIGS. 1 and 3  to  5  comprises an intake camshaft adjuster  1  and an exhaust camshaft adjuster  2 . On the crankshaft  3 , a chain wheel  4  is fixedly mounted which is drivingly connected by chain  5  to the chain wheel  6  of the exhaust camshaft adjuster  2 . The chain wheel  6  can be a single track wheel or double track wheel. As illustrated in  FIGS. 3  to  5 , the chain wheel  6  in the illustrated embodiment is of a double track configuration and has accordingly two gear rings  7  and  8 . The chain wheel  6  is connected by means of a spacer member  9  to a gear in the form of a gear ring  10  that is advantageously a monolithic part of the stator  11 . The stator  11  surrounds, as is known in the art, the rotor that is fixedly mounted on the exhaust camshaft  12 . As illustrated in  FIG. 3 , the stator  11  has a cylindrical wall  13  projecting past the gear ring  10  in the axial direction and comprising at least one positive-locking element in the form of a recess  14  extending the axial direction. In the illustrated embodiment, the recess  14  has a part-circular cross-section. A matching counter locking element in the from of a projection  15  engages this recess  14  in a positive-locking way. This projection  15  is provided on the inner side of the chain wheel  6 . By means of the recess  14  and the projection  15 , a radial alignment of the chain wheel  6  relative to the stator  11  that is part of the camshaft adjuster  2  is realized. The spacer member  9  and the chain wheel  6  are pushed onto the peripheral wall  13 . Subsequently, the spacer member  9  and the chain wheel  6  are connected by screws  16  to the stator  11  and the gear ring  10 . 
     The gear ring  10  has a greater inner diameter than the peripheral wall  13  of the stator  11 . Webs  17  that are uniformly distributed about the circumference project from the inner side of the gear ring  10 . The webs  17  connect the gear ring  10  to the stator wall  13 . The webs  17  have threaded bores  18  into which the screws  16  can be screwed. 
     The spacer member  9  has widened portions  19  distributed circumferentially about the member  9  and projecting past both end faces of the spacer member  9 . The widened portions  19  each have an opening  20  for passing the screws  16  therethrough. 
     The chain wheel  6  has an inner circumferentially extending flange  21  that is located at approximately half the width of the chain wheel  6  and is provided with openings  22  distributed about the circumference for passing the screws  16  therethrough. Since the flange  21  is recessed relative to the end faces of the chain wheel  6 , the heads  23  of the screws  16  are recessed within the chain wheel  6  (FIG.  4 ). The spacer member  9  positions the chain wheel  6  at an axial spacing relative to the gear ring  10 . 
     On the end face of the stator wall  13  facing the chain wheel  6  a cover plate  24  ( FIG. 4 ) is fastened by means of screws  25 . As is known in the art, the cover plate  24  secures axially the rotor that is fixedly fastened on the camshaft  12  (FIG.  1 ). On the opposite end face of the wall  13  of the stator  11  an annular disk  26  is secured by screws  27  that secures the rotor in the other axial direction on the stator  11 . 
     The chain  5  of the camshaft adjusting device is guided about the chain wheel  6  (FIG.  1 ). The gear ring  10  engages a gear in the form of a gear ring  28  of the intake camshaft adjuster  1  ( FIG. 1 ) that is fixedly connected to the stator  11 ; preferably, it is a monolithic part of the stator  11 . Advantageously, the gear rings  10 ,  28  have the same diameter. 
     Since the intake camshaft adjuster  1  and the exhaust camshaft adjuster  2  directly engage one another by means of the gear rings  10 ,  28 , the two camshafts  12 ,  29  can be arranged adjacent to one another at a minimal spacing. In this way, the camshaft adjusting device can be mounted easily even for cramped mounting conditions because the chain drive is provided only between the gear wheel  4  on the crankshaft  3  and the chain wheel  6  of the camshaft adjuster  2 . 
     The chain wheel  6  can be fastened in the described way easily on the stator wall  13 . The crankshaft  3  is connected by means of the chain  5  to the camshaft  12  which, in turn, is drivingly connected via the gear rings  10 ,  28  to the camshaft  29 . The gear ring  10  and the chain wheel  6  can be manufactured of different materials so that an optimal material adjustment of these parts is possible with regard to the specific use of the adjusting device. 
     In the embodiment of  FIG. 6 , the intake camshaft adjuster  1  and the exhaust camshaft adjuster  2  are not directly engaging one another by means of the gear rings  10 ,  28 . The camshaft adjusting device has an intermediate shaft  30  that is positioned parallel to the crankshaft  3  and the camshafts  12 ,  29  and supports a gear wheel  31  fixedly connected thereto. The gear wheel  31  engages the gear rings  10 ,  28  of the two camshaft adjusters  1 ,  2 . There is also a chain wheel  32  mounted fixedly on the intermediate shaft  30  for receiving the chain  5 . The crankshaft  3  drives thus by means of the chain drive  4 ,  5 ,  32  the intermediate shaft  30  that, in turn, drives via the gear wheel  31  the camshaft adjusters  1 ,  2  in the described way. The gear wheels  31  and gear rings  10 ,  28  have advantageously the same diameter. However, it is possible to provide the gear wheel  31  with a diameter that is different from that of the gear rings  10 ,  28  so that, depending on the diameter ratio, a reduction gearing or step-up gearing is enabled. 
     This embodiment is also characterized in that it can be mounted in a simple way even under cramped or tight mounting conditions. The chain drive is provided only between the gear wheel  4  of the crankshaft  3  and the gear wheel  31  of the intermediate shaft  30 . 
     While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.