Patent Publication Number: US-8991343-B2

Title: Camshaft adjusting device

Description:
FIELD OF THE INVENTION 
     The present invention relates to a camshaft adjusting device for changing the relative angular position of a camshaft relative to a crankshaft of an internal combustion engine, wherein the camshaft adjusting device comprises an actuator for activating a hydraulic valve, wherein the actuator is attached to a housing element by an attachment means, and wherein the actuator has an axis that is concentric to an axis of the camshaft adjusting device in the installed state of the actuator. 
     BACKGROUND 
     Camshaft adjusters of this class are used for changing the relative angular position of the camshaft relative to the crankshaft of an internal combustion engine. Here, the adjusting device comprises a drive element that is driven by the crankshaft via a gear and is supported so that it can rotate relative to the camshaft, wherein at least two hydraulic chambers are formed between the drive element and the camshaft and these hydraulic chambers can be pressurized with a pressurized fluid, in order to set a defined relative rotational position between the drive element and the camshaft. 
     The pressurized fluid is controlled with hydraulic valves. For central valve systems, an actuator in the form of a central magnet is mounted coaxial to the camshaft by a flange separated from the associated hydraulic system in a position-fixed structure of the motor (housing element, e.g., the timing gear cover). Current is fed into a coil of the electromagnet by a connector. The magnetic field induced in this way is transmitted to a moving magnetic armature via a soft iron core consisting of a yoke, yoke plate, magnetic housing, and pole core. It exerts a magnetic force on the armature in the direction of the gap reduction across a working air gap between the pole core and the armature. This magnetic force is transmitted to a piston of the central valve via a pressure pin. The volume flow of the pressurized fluid to the camshaft adjuster is changed by the displacement of the piston. 
     The actuator of the camshaft adjuster is attached to the housing element in the prior art usually by a screw connection. Such solutions are disclosed, for example, in DE 102 11 467 A1, DE 10 2007 019 923 A1, and DE 10 2006 031 517 A1. 
     A screw-less fastening of the actuator on the housing element has also become known, as mentioned in passing in DE 102 52 431 A1. A bayonet mount can be used here to fix the actuator on the housing element. In this case, the actuator that is to be mounted concentric to the axis of the camshaft adjuster is mounted by a rotational movement after which it is inserted into a corresponding handle section of the bayonet mount. 
     A disadvantage in this procedure is that it sometimes difficult for the installer to perform the rotational or pivoting movement, because this must be performed with a certain, not insignificant torque produced by the requirement for a fixed seating of the actuator in the installed state and the required fitting tolerances between the actuator and housing element. 
     SUMMARY 
     The present invention is based on the objective of improving a camshaft adjusting device of the type noted above such that the mentioned disadvantage can be avoided. Accordingly, a construction is proposed through which the installation of the actuator on the camshaft adjuster can be simplified, i.e., is easier to perform. 
     This objective is met by the invention being characterized in that the actuator has, on its outside facing away from the camshaft adjusting device, a handle section with a shape that is not rotationally symmetric to the axis. 
     The attachment means are here preferably constructed as a screw-free fastening element; in particular, a bayonet mount is envisioned as the attachment means. 
     The handle section can have polygonal contours. These polygonal contours are preferably arranged about the axis. The handle section is provided, in an especially preferred way, with quadrilateral, pentagonal, hexagonal, heptagonal, or octagonal contours. 
     The handle section can alternatively also have a vane-like structure with two handle sections. 
     Furthermore, the handle section could have a pair of knobs with two handle sections. 
     The outside of the actuator together with the handle section is preferably formed by an injection-molded housing element. An electric connector can be integrated into the housing element. 
     Through the proposed solution, it is much easier for an installer to attach the actuator onto the camshaft adjuster housing. The required torque to be applied here by hand can be generated much more easily by the proposed handle section. The mentioned handle section on the outside of the actuator in the form of polygonal contours can also be constructed alternatively as a vane or as a pair of knobs. The decisive factor is the ability to apply a pair of forces onto the outside of the actuator via the palm, the fingers, and the thumbs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings, an embodiment of the invention is shown. Shown are: 
         FIG. 1  in perspective view, the end region of a camshaft adjuster in which an actuator for actuating a hydraulic valve is mounted, 
         FIG. 2  the actuator in a radial section view, 
         FIG. 3  the actuator in a perspective view, seen from a first direction, 
         FIG. 4  the actuator in a perspective view, seen from a second direction. 
         FIG. 5  the actuator in a front view, 
         FIG. 6  the actuator in a rear view, and 
         FIG. 7  the actuator in a side view. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In  FIG. 1 , a camshaft adjusting device  1  is sketched, with only a part of this device being visible, namely one axial end region. In this region, an actuator  2  is arranged that is used for adjusting a hydraulic valve. 
     The camshaft adjusting device  1  is here constructed according to the construction with a central magnet and central valve for the adjustment, as described in DE 102 52 431 A1 of the applicant; this document is referenced explicitly. The actuator  2  is attached to a housing element  4  of the camshaft adjusting device  1 . 
     Details can be taken from  FIG. 2 . In the central valve application to be seen here for the camshaft adjusting system, a magnet is mounted in a position fixed structure of the engine (e.g., in the timing gear cover) coaxial to the camshaft by a flange  10  separately from the associated hydraulic system. Current is fed into a coil  11  via an electric connector  9 . The magnetic field induced in this way is transmitted to the moving magnetic armature  16  via a soft iron core consisting of yoke  12 , yoke plate  13 , magnetic housing  14 , and pole core  15 . The magnetic field exerts a magnetic force on the magnetic armature  16  in the direction of the gap reduction across a working air gap between the pole core  15  and the magnetic armature  16 . This magnetic force is transmitted by a pressure pin  17  onto the piston of a (not shown) hydraulic central valve. 
     The displacement of the piston changes the hydraulic volume flows in the camshaft adjuster and thus rotates the camshaft relative to the crankshaft in a known way. 
     The actuator  2  on the housing element  4  of the camshaft adjusting device  1  is attached in the present case by a bayonet mount (“tank cover closure”), i.e., the attachment means  3  with which the actuator  2  is attached to the housing element  4  is constructed as a screw-free connecting means. In  FIG. 1 , cut regions  3  are to be seen that are constructed for placement in corresponding (not shown) projections extending outward in the radial direction on the housing element  4 ; rotating the actuator  2  about the axis  5  (see  FIG. 2 ) closes the bayonet mount and fixes the actuator  2  on the housing element  4 . 
     So that the installer can apply the required torque by hand without a problem onto the actuator  2  during the process of attaching the actuator  2  on the housing element  4 , it is provided that the actuator  2  has a handle section  7  with a shape that is not rotationally symmetric to the axis  5  on its outside  6  facing away from the camshaft adjusting device  1 , as can be seen, in particular, in  FIGS. 3 and 5 . 
     Accordingly, the outside  6  of the actuator  2  does not have a rotationally symmetric construction (apart from the electrical connector  9  that is otherwise not suitable for applying a torque), but instead has handle-like contours. 
     In the embodiment, the handle section  7  is provided with octagonal contours, so that contact surfaces can be found for the thumbs and fingers of the installer&#39;s hand, in order to turn the actuator  2  during installation about the axis  5 , wherein in this way the hand of the installer finds a good grip, so that it cannot slip. 
     In  FIGS. 3 to 7 , the actuator  2  is to be seen as a separate component in different views (in  FIG. 3 : the front side in a perspective diagram; in  FIG. 4 : the rear side in a perspective diagram; in  FIG. 5 : the view in the axial direction  5  seen from the front; in  FIG. 6 : the view in the axial direction  5  seen from the rear; in  FIG. 7 : the side view). In  FIGS. 3 and 5 , the construction of the handle section  7  as octagonal contours can be seen in an especially good way. 
     The construction of a housing element  8  of the actuator  2  as a completely insert-molded component is preferred in which the connector  9  or at least its projection is also integrated. In the injection molding of the housing element  8 , the handle section  7  is formed accordingly. 
     LIST OF REFERENCE SYMBOLS 
     
         
           1  Camshaft adjusting device 
           2  Actuator 
           3  Attachment means 
           4  Housing element 
           5  Axis 
           6  Outside 
           7  Handle section 
           8  Housing element 
           9  Electric connector 
           10  Flange 
           11  Coil 
           12  Yoke 
           13  Yoke plate 
           14  Magnetic housing 
           15  Pole core 
           16  Magnetic armature 
           17  Pressure pin