Abstract:
The invention relates to a starter system for an internal combustion engine, in particular in motor vehicles, having a starter motor, a reduction gear, and a pinion-engaging assembly. 
     The primary components of the starter system ( 10 ) are embodied as individual modules and can be expanded in variable ways to make starter systems ( 10 ) with different parameters.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a starter system for an internal combustion engine, in particular, for motor vehicles. 
     It is known that internal combustion engines have to be cranked until they reach the point where they run on their own. To that end, so-called starter systems are used in motor vehicles. These starter systems include a starter motor, supplied by a motor vehicle battery, a reduction gear, and a pinion-engaging assembly. For starting the engine, the starter motor is connected to the motor vehicle battery via a starter switch (ignition switch). Once the starter motor is put in operation, a pinion is made to engage a ring gear disposed on a crankshaft of the engine, so that the engine can be cranked. Since the starter motors have a substantially higher rpm than what is required to crank the engine, these different rotary speeds are adapted via a reduction gear. The reduction gear is typically embodied as a planetary gear, with the sun wheel drivable by the starter motor and the crankshaft operatively connected to the planet wheels. 
     A crankshaft torque required to crank the engine and a minimum crankshaft rpm depend on engine parameters, such as stroke volume, number of cylinders, compression, friction losses, temperature, and additional loads. Thus a starter system has to be adapted to the parameters of the engine. In particular, there is a need for starter systems with different starting power levels and/or different starting rotary speeds. 
     In the known starter systems, it is disadvantageous that for the sake of high utilization of installation space, they are embodied in a so-called inter-nested way, and that to adapt the starter power and/or the starting rotary speed of the starter, many different-sized starter systems are needed. Adapting to altered parameters of an engine can be done only by redimensioning or reconstructing the entire starter system. 
     SUMMARY OF THE INVENTION 
     The starter system of the invention offers the advantage over the prior art that adaptation to engines of different parameters can be done in a simple way. Because the primary components of the starter system are embodied as individual modules and can be expanded variably into starter systems with different parameters, it is simple, beginning with the individual modules, to achieve different starter systems without having to reconstruct the entire starter system. 
     In a preferred feature of the invention, it is provided that the starter system includes a drive module, a gear module and an electronic module. This makes it possible for the primary components of the starter system to be optimized individually to desired starting parameters, so that the desired starter system with the requisite parameters can be assembled from the existing variously-sized individual modules. It is also preferable for a drive module to be combinable with different gear modules, so that adapting the starter system to a desired crankshaft rpm can be done solely via the gear modules. Thus the same type of drive modules can be combined with the appropriate gear modules. On the other hand, it is equally possible for different crankshaft torques to be attained via drive modules with different power level parameters but the same gear modules. 
     Overall, it becomes clear that by the modular design of the starter system provided for by the invention, identical component groups can be used for different starter system power level classes. By taking standard sizes into account in the individual component groups, these groups can be accordingly assembled in final form economically, thus reducing both the effort and cost of production. In particular, this also makes for high flexibility in final assembly of the starter system, especially when making a rapid adaptation to altered application requirements of different internal combustion engines. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is described in further detail below in terms of exemplary embodiments in conjunction with the associated drawings. Shown are: 
     FIG. 1, a sectional view through a starter system of the invention in a first exemplary embodiment; 
     FIG. 2, primary component groups of the starter system of FIG. 1; 
     FIG. 3, a sectional view through a starter system in a second exemplary embodiment; and 
     FIG. 4, a block diagram illustrating the production of the starter systems of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows a starter system, identified overall by reference numeral  10 , for an internal combustion engine, not shown. Inside a housing  12 , the starter system  10  includes a starter motor  14  and a reduction gear  16  embodied as a planetary gear. The structure and function of such starter systems  10  are known, so that these will not be addressed further in the present description. 
     In FIG. 2, sectional views of the two primary groups of the starter system are shown, in the state before final assembly. The drive motor  14  forms a drive module  18 , and the reduction gear  16  forms a gear module  20 . The starter motor  14  is a direct current motor, whose structure and function are likewise well known. An armature shaft  22  of the starter motor  14  has a pinion  24 , which is disposed on the armature shaft  22  in a manner fixed against relative rotation. The armature shaft  22  is extended past the housing  26  of the starter motor  14  and can be introduced into a guide  28  of the reduction gear  16 . When the drive module  18  is mounted to the gear module  20 , the armature shaft  22  engages the guide  28 , so that the slip-on pinion  24  meshes planet wheels  30  of the reduction gear  16 . The slip-on pinion  24  thus forms the sun wheel of the reduction gear (planetary gear)  16 . An output shaft  32  of the gear module  20  has a pinion  34 , which in a manner known per se can be made to engage a ring gear disposed on a crankshaft of the engine. 
     Depending on a demand for rotary speed and/or torque for starting (cranking) the engine, the starter system  10  can be dimensioned accordingly by a suitable choice of the drive module  18  and/or gear module  20 . The torque can be achieved by choosing a power level of the starter motor, which can range between 0.7 kW and 2.3 kW, for instance. The adaptation to a required rotary speed can be done by means of a gear ratio of the reduction gear  20 , and by the choice of a suitable slip-on pinion  24 , the gear ratio can be varied, with otherwise the same drive module  18  and gear module  20 . It becomes clear that at little effort or expense, starter systems  10  for different requirements can thus be furnished in a simple way, for instance with regard to a crankshaft torque and/or a crankshaft rpm. The various basic components of the starter system  10  can be made economically by mass production, since a specific adaptation is possible either by selecting the drive module  18  and/or selecting the slip-on pinion  24  and/or the gear module  20 . 
     A free-wheel mechanism of the starter system  10  is integrated with the reduction gear  20 . This free-wheel mechanism disconnects the starter motor  14  from the crankshaft of the internal combustion engine once this engine is at a minimum rpm. This averts the possibility of damage to the drive motor  14  when the armature rpm is exceeded by the crankshaft rpm. 
     FIG. 3 shows a modified starter system  10 , in which in addition to the drive module  18  and the gear module  20 , an electronic module  36  is integrated. The electronic module  36  takes on control functions for the starter system  10 , such as a start/stop function, current clocking and/or an immobilizer function. Such functions are likewise known. Of interest to the present invention is the fact that the electronic module  36  is integrated as a compact module into the housing  12  of the starter system  10 . The electronic module  36  can for instance be flanged to the drive module  18 . To span the axial length of the electronic module  36 , the armature shaft  22  is embodied as correspondingly longer, so that it can engage the guide portion  28  of the gear module  20 . It is quite clear from FIG. 3 that by replacing the electronic module  36 , different functions of the starter system  10  can easily be incorporated into the starter system  10  as desired by the user. The other components, the drive module  18  and the gear module  20 , remain untouched by such an adaptation. 
     Overall, it can be stated that each of the individual modules, that is, the drive module  18 , the electronic module  36  and/or the gear module  20 , can be optimized on its own. These modules are standardized in the sense that in the final assembly of starter systems  10 , various drive modules  18 , electronic modules  36  and gear modules  20  that are in stock can be combined selectively with one another. The sole decisive factor is what the user of the starter system  10  requires. 
     FIG. 4, in a block circuit diagram, illustrates the final assembly of starter systems  10  from different modules. Block  40  indicates the production of the drive modules  18 , block  42  the production of the gear modules  20 , and block  44  the production of the electronic modules  36 . For producing the drive modules  18 , it is shown in suggested form inside the complex  40  for instance that the armature shaft is furnished in a step  46 , the armature assembly is done in a step  48 , the pole housing assembly is done in a step  50 , and finally the assembly of the drive module  18  is done in a step  52 . 
     Depending on the application demand made of the starter system  10 , the appropriate drive module  18 , the appropriate gear module  20  and the appropriate electronic module  36  are then completed in a final step  54  to make the desired starter system  10 . By means of the modular construction explained, in which the individual modules are compatible with one another even given different power level parameters and speed-increase parameters, the production of starter systems  10  can be simplified considerably and thus made more economical.