Abstract:
The invention relates to a relay ( 16 ), especially for electrical starting devices for internal combustion engines. The relay ( 16 ) comprises a relay armature ( 168 ) and an armature return element ( 171 ). A fluid, enclosed in a hollow space ( 236 , Δs), between the relay armature ( 168 ) and the armature return element ( 171 ) pneumatically damps the collision between the relay armature ( 168 ) and the armature return element ( 171 ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    DE 101 24 506 A1 relates to a starter for a motor vehicle. The starter comprises a pole housing which contains the starter motor, an engagement relay which is arranged parallel to said pole housing and contains a solenoid switch, an engagement lever, which is rotatably mounted with a transition region between the pole housing and the engagement relay, for coupling the starter motor to the internal combustion engine. A seal to prevent the ingress of contaminants and moisture into the engagement relay is also provided. The seal is formed by a rubber diaphragm, which is connected to the housing walls, within the transition region between the pole housing and the engagement relay. 
         [0002]    DE 195 49 179 A1 relates to an engagement relay for a starter apparatus. The engagement relay comprises a contact bridge which bridges at least two contact pins in the switched-on state and which is fitted to a moving switching spindle. The contact bridge has in each case at least two defined contact areas which are associated with one contact pin and which are provided on spring arms which are flexible in their longitudinal extent and transverse to their longitudinal extent. 
         [0003]    Whereas approximately 40 000 starting processes are completed over the service life of a vehicle in conventional electrical starting apparatuses for internal combustion engines, up to half a million and more switching processes are carried out in starters which are employed in internal combustion engines with a start/stop functionality. This means that the electrical starting apparatus has to be correspondingly designed. 
         [0004]    The electrical starting apparatus accordingly has to be designed for such a high number of switching cycles and complete these without problems. It has been found that relatively high demands are made of the acoustics of the electrical starting apparatus in passenger cars which are equipped with a start/stop functionality. Noises which are produced by metal elements being struck in the components of a starter, in particular an electrical starting apparatus, are found to cause discomfort and to be disturbing. 
       SUMMARY OF THE INVENTION 
       [0005]    In order to reduce the noise level when operating an electrical starting apparatus, the invention proposes pneumatically providing pneumatic damping between components which move relative to one another, in particular a linearly moving relay armature and an armature return. When power is supplied to the magnet coils of the relay of an electrical starting apparatus, the relay armature which is displaceably guided in the relay housing moves toward an armature return which is arranged in a stationary manner in the relay. Both the end faces of the relay armature which moves relative to the armature return and those of the armature return have a mutually complementary geometric contour and form a hollow space which is filled with a fluid, in particular air. 
         [0006]    By virtue of providing suitable sealing measures, for example providing a V-shaped sealing lip or a sealing ring which is fitted to the casing surface of the relay armature which moves relative to the relay housing, the volume of fluid which remains in the hollow space between the relay armature and the armature return is sealed off to prevent losses, that is to say leakage, and therefore the volume of fluid can be used as a fluid cushion for damping the stopping movement of the end face of the relay armature against the corresponding end face of the armature return, it being possible for this to be used to drastically reduce the momentum of the moving relay armature and accordingly to reduce its energy. Examples of a fluid are air or another gas and also a liquid. The volume of fluid remaining in the hollow space between the end face of the relay armature and the correspondingly designed end face of the armature return forms a fluid cushion which damps the stopping movement of the end face of the relay armature as it moves into the relay housing and accordingly damps the striking movement, which is produced when contact is made between the end face of the relay armature and the end face of the armature return, by virtue of a reduction in energy. 
         [0007]    The denser the volume of fluid within the hollow space between the end face of the relay armature and the end face of the armature return can be kept, the greater the damping effect that can be achieved with the solution proposed according to the invention on account of the low leakage losses. Instead of the V seal between the circumference of the relay armature and the relay housing, it is also possible to form a precise transition fit, for example a H7/g6 fit, in order to keep the leakage losses, that is to say the flow of fluid out of the hollow space between the end faces of the relay armature and the armature return, as low as possible. 
         [0008]    In a further variant embodiment for the pneumatic damping of a relay as proposed according to the invention, in particular for operating or for initializing an electrical starting apparatus, the relay armature can contain a longitudinal bore. Said longitudinal bore is connected both to the hollow space between the end face of the relay armature and to the surrounding area. Furthermore, a longitudinal bore, which issues into the hollow space between the end face of the relay armature and the end face of the armature return at one end and into a relief space in the relay housing at the other end, likewise extends through the thickness of the armature return. A valve, for example a non-return valve, can be incorporated in this channel which connects the hollow space to the relief space. If the valve is in the form of a non-return valve, for example, it is oriented in such a way that it closes when the volume of fluid within the hollow space between the end faces of the relay armature and armature return is compressed, and thereby prevents a volume of fluid from flowing out of this hollow space. In one possible variant embodiment of the solution proposed according to the invention, when a valve is provided in the armature return, a main channel, which can be closed by a valve element, and an auxiliary channel, which issues next to the closing element and is always open, for example, issue at the valve seat of said valve. The flow cross sections of the main channel and the auxiliary channel preferably have a size such that the flow cross section of the main channel is larger than the flow cross section of the auxiliary channel. If the volume of fluid in the hollow space between the end face of the relay armature and the end face of the armature return is compressed, the closing element is pushed into the seat and closes the main channel. In accordance with the design of the flow cross section of the auxiliary channel which stays open, the volume of fluid flows out of the hollow space between the end face of the relay armature and the end face of the armature return in a throttled manner, and therefore a volume of fluid which damps the stopping movement of the end face of the relay armature against the end face of the armature return is maintained in the hollow space, this being only partially relieved of pressure into the relief space by means of the auxiliary channel which serves as an outflow channel when the volume of fluid is compressed. 
         [0009]    In a further variant embodiment of the solution proposed according to the invention for the pneumatic damping of the relay armature and armature return, by way of example, a guide bush which surrounds a switching pin can be provided with a number of openings, for example transverse bores. These transverse bores allow, depending on the degree of opening of said transverse bores, the volume of fluid to flow out via the openings, depending on the degree of opening of said openings, in the event of a relative displacement with respect to the armature return which is arranged in the relay in a stationary manner. The guide bush serves, depending on the operating path of the switching pin, as a slide, with the volume of fluid flowing out of the hollow space between the relay armature and the armature return of the relay being defined by the degree of opening or degree of overlap of the openings which are formed in the wall filling bush. The volume which flows out of the hollow space between the relay armature and the armature return via the openings in the wall of the guide bush flows into the relief space in the relay. 
         [0010]    In a further variant embodiment of the solution proposed according to the invention, when a specific travel movement, that is to say a specific distance ΔS between the end face of the relay armature and the end face of the armature return which is arranged in the relay in a stationary manner, is achieved, a valve can be operated by the end face of the relay armature itself. To this end, a peg-like valve element is provided in the armature return, said valve element being prestressed by means of a spring and being in the closed state as the end face of the relay armature approaches. If the end face of the approaching relay armature strikes an end of the peg-like valve when the distance Δs is reached, said valve is opened as the relay armature gets closer, and therefore fluid flows out of the hollow space, which is defined by the distance Δs, between the end face of the relay armature and the end face of the armature return, which is accommodated in the relay in a stationary manner, only when the distance Δs is reached, and a counterpressure is built up and maintained in order to reach the distance Δs, said counterpressure counteracting the stopping movement of the end face of the relay armature against the end face of the armature return of the relay in a damping manner. 
         [0011]    A channel in which the peg-like valve element in the armature return is accommodated can preferably be formed in such a way that said channel is connected to a slot by means of which a volume of fluid flows out of the remaining hollow space, which is defined in accordance with the distance Δs, between the end face of the relay armature and the end face of the armature return when the peg-like valve element is operated by the end surface of the relay armature. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The invention will be described in greater detail below with reference to the drawing, in which: 
           [0013]      FIG. 1  shows a longitudinal section through a starting apparatus, 
           [0014]      FIG. 2  shows a schematic illustration of the relay having a relay armature and an armature return, 
           [0015]      FIG. 3  shows a variant embodiment of a valve in the form of a non-return valve, 
           [0016]      FIG. 4  shows a guide bush, which acts as slide, in the armature return, accommodated on a switching pin which is not illustrated in  FIG. 4 , 
           [0017]      FIG. 5  shows a V lip formed in a circumferential slot in the relay armature, 
           [0018]      FIG. 6  shows a valve which is operated when a distance Δs is reached between the end face of the relay armature and the end face of the armature return which is arranged in the relay armature in a stationary manner, and 
           [0019]      FIG. 6.1  shows a section through a channel having a slot in the armature return of the relay. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]      FIG. 1  shows a starting apparatus  10 . This starting apparatus  10  has, for example, a starter motor  13  and a relay  16 . The starter motor  13  and the relay  16  are attached to a common drive end plate  19 . The starter motor  13  has the functional task of driving a starter pinion  22  which is generally in the form of a spur gear. The starter pinion  22  meshes with a ring gear  25  of an internal combustion engine, which is not illustrated in  FIG. 1 . 
         [0021]    The starter motor  13  has, as a housing, a pole tube  28  which has pole shoes  31  on its inner circumference, with a field winding  34  being wound around each of said pole shoes. The pole shoes  31  in turn surround an armature  37 , which has an armature stack  43  comprising laminations  40  and an armature winding  49  arranged in slots  46 . The armature stack  43  is pressed onto a drive shaft  44 . Furthermore, a commutator  52  is fitted at that end of the drive shaft  44  which is remote from the starter pinion  22 , said commutator comprising, inter alia, individual commutator laminations  55 . The commutator laminations  55  are electrically connected to the armature winding  49 , in a known manner, in such a way that, when power is supplied to the commutator laminations  55  by carbon brushes  58 , a rotary movement of the armature  37  is produced in the pole tube  28 . A power supply line  61  which is arranged between the meshing relay  16  and the starter motor  13  supplies power to both the carbon brushes  58  and the field winding  34  in the switched-on state. The drive shaft  44  is supported on the commutator side by a shaft journal  64  and a sliding bearing  67  which in turn is held fixed in position by a commutator bearing cap  70 . The commutator cap  70  is in turn fixed in the drive end plate  19  by means of tension rods  73 , which are arranged distributed over the circumference of the pole tube  28  (screws, for example two, three or four pieces). In the process, the pole tube  28  is supported on the drive end plate  19 , and the commutator bearing cap  70  is supported on the pole tube  28 . 
         [0022]    In the drive direction, the armature  37  is adjoined by a sun gear  80 , which is part of a planetary gear mechanism  83 . The sun gear  80  is surrounded by a plurality of planet gears  86 , usually three planet gears  86 , which are supported by means of roller bearings  89  on axle journals  92 . The planet gears  86  roll in a hollow wheel  95 , which is mounted externally in the pole tube  28 . In the direction toward the output drive side, the planet gears  86  are adjoined by a planet carrier  98 , in which the axle journals  92  are accommodated. The planet carrier  98  is in turn mounted in an intermediate bearing  101  and a sliding bearing  104  which is arranged therein. The intermediate bearing  101  is configured in the form of a pot in such a way that both the planet carrier  98  and the planet gears  86  are accommodated in said intermediate bearing. Furthermore, the hollow wheel  95  is arranged in the pot-shaped intermediate bearing  101  and is ultimately closed by a cover  107  with respect to the armature  37 . The intermediate bearing  101  is also supported by way of its outer circumference on the inner face of the pole tube  28 . The armature  37  has a further shaft journal  110  on that end of the drive shaft  44  which is remote from the commutator  52 , said shaft journal likewise being accommodated in a sliding bearing  113 . The sliding bearing  113  is in turn accommodated in a central bore in the planet carrier  98 . The planet carrier  98  is integrally connected to the output drive shaft  116 . This output drive shaft  116  is supported by its end  119  which is remote from the intermediate bearing  101  in a further bearing  122 , the A bearing, which is formed in the drive end plate  19 . The output drive shaft  116  is divided into various sections: a section with a straight gearing  125  (inner gearing) which is part of a shaft-hub connection  128  thus follows the section which is arranged in the sliding bearing  104  of the intermediate bearing  101 . This shaft-hub connection  128  makes it possible in this case for a driver  131  to perform an axially linear sliding movement. This driver  131  is a sleeve-like protrusion, which is integral with a pot-shaped outer ring  132  of the freewheel  137 . This freewheel  137  (ratchet) furthermore comprises the inner ring  140 , which is arranged radially within the outer ring  132 . Clamping bodies  138  are arranged between the inner ring  140  and the outer ring  132 . The clamping bodies  138 , in interaction with the inner and the outer ring, prevent a relative movement between the outer ring and the inner ring in a second direction. The freewheel  137  allows a relative movement between the inner ring  140  and the outer ring  132  in only one direction. In this exemplary embodiment, the inner ring  140  is integrally formed with the starter pinion  22  and the helical gearing  143  (outer helical gearing) thereof. 
         [0023]    The relay  16  has a pin  150 , which constitutes an electrical contact and is connected to the positive terminal of an electrical starter battery (not illustrated in  FIG. 1 ). This pin  150  is passed through a relay cover  153 . This relay cover  153  closes off a relay housing  156 , which is fastened to the drive end plate  19  by means of a plurality of fastening elements  159  (screws). A pull-in winding  162  and a holding winding  165  are furthermore arranged in the relay  16 . The pull-in winding  162  and the holding winding  165  both each induce an electromagnetic field in the switched-on state, said electromagnetic field flowing through both the relay housing  156  (composed of electromagnetically conductive material), a linearly moving armature  168  and an armature return  171 . The armature  168  has a push rod  174 , which is moved in the direction of a switching pin  177  during linear pull-in of the armature  168 . With this movement of the push rod  174  toward the switching pin  177 , said switching pin is moved out of its rest position in the direction toward two contacts  180  and  181 , so that a contact bridge  184 , which is fitted at the end of the switching pin  177 , electrically connects the two contacts  180  and  181  to one another. As a result, electrical power is passed from the pin  150 , beyond the contact bridge  184 , to the power supply line  61  and therefore to the carbon brushes  58 . Power is supplied to the starter motor  13  in the process. 
         [0024]    However, the relay  16  and the armature  168  furthermore also have the task of moving, with a pull element  187 , a lever which is arranged in the drive end plate  19  such that it can rotate. The lever  190 , usually in the form of a forked lever, engages with two “prongs” (not shown here) on its outer circumference around two disks  193  and  194  in order to move a driver ring  197 , which is trapped between said disks, toward the freewheel  137  counter to the resistance of the spring  200  and thereby to mesh the starter pinion  22  with the ring gear  25  of the internal combustion engine. 
         [0025]      FIG. 2  shows a schematic section through the relay for operating the starting apparatus according to  FIG. 1  on an enlarged scale. 
         [0026]    The illustration according to  FIG. 2  shows a relay for operating an electrical starting apparatus on an enlarged scale. 
         [0027]      FIG. 2  shows that the relay  16  has a linearly moving armature, that is to say a relay armature  168 , the end face  206  of said armature corresponding to the end face of the armature return  171  which is accommodated in the relay housing  156 . A hollow space  236 , which is filled with a fluid, for example air, is formed between the end face  206  and that end face of the armature return  171  which is situated opposite said end face  206 . A channel  204  which issues at a mouth  208  in the end face  206  of the relay armature  168  passes through the relay armature. 
         [0028]    A channel  210  likewise passes through the armature return  171 , a valve, which is illustrated on an enlarged scale in  FIG. 3 , for example in the form of a non-return valve  212 , being accommodated in said channel. 
         [0029]    Both the channel  204  in the relay armature  168  and the channel  210  in the armature return  171  have a diameter of only a few mm. The channel  204  in the relay armature  168  extends from the mouth  208 , runs through the relay armature  168 , and issues in the external area surrounding the relay  16 . 
         [0030]    The channel  210 , which passes through the armature return  171 , connects the hollow space  236  to a relief space  253  on that side of the armature return  171  which is averted from the relay armature  168  and is accommodated in the relay housing  156  of the relay  16  in a stationary manner. Reference symbol  153  denotes a relay cover of the relay  16 . 
         [0031]      FIG. 3  shows a valve which is in the form of a non-return valve  212  and is arranged in the channel  210  of the armature return  171 . A spring-loaded, in this case spherical, closing element  214  is provided in the valve  212  which is in the form of a non-return valve, said closing element being pushed by the spring into a seat  216  which is formed in the armature return  171 . Both a main channel  218 , which has a first diameter D 1 , compare reference symbol  220 , and an auxiliary channel  220 , which has a smaller, second diameter D 2 , compare item  224 , extend from the seat  216  of the valve  212 . While the main channel  218  is closed when the closing element  214  is in its seat  216 , this is not the case for the auxiliary channel  220  which is still permeable but has a second, smaller diameter D 2 , compare item  224 , than the first diameter D 1 , compare item  222  of the main channel  218 , in the closed state of the closing element  214 . 
         [0032]    In the variant embodiment of a pneumatic damping arrangement illustrated in  FIGS. 2 and 3 , the volume of fluid which is contained in the hollow space  236  is compressed as the end surface  206  approaches in the event of a linear movement of the relay armature  168  in the direction of the end face of the armature return  171 . As a result, the energy of the relay armature  168  which is moving toward the armature return  171  is reduced. On account of the build-up of pressure, the non-return valve  212  closes the seat  216  and therefore the main channel  218 , while a flow of fluid through the auxiliary channel  200 , which is not closed by the closing element  214  and issues into the relief space  253 , can be reduced. This results in a gradual reduction in pressure in the hollow space  236 , with the pressure level, however, being kept at a level such that the end surface  206  of the relay armature which is moving toward the armature return  171  does not come to a hard stop and the development of noise due to hard contact between the metals of the end surface  206  at that end surface of the relay armature  171  which corresponds to said end surface  206  is precluded. 
         [0033]    The illustration according to  FIG. 4  shows that hydraulic damping can also be achieved by a guide bush, which is accommodated on the switching pin  177 , in this variant embodiment. 
         [0034]    In this variant embodiment, compare the illustration according to  FIG. 1 , the guide bush  202 , which is accommodated on the switching pin  177 , is provided with a number of openings  230  and  232  which can be in the form of, for example, transverse bores which run through the wall of the guide bush  202 . 
         [0035]    In the illustration according to  FIG. 4 , the guide bush  202  having openings, which are in the form of transverse bores  230  and  232 , is placed in a first position  226  which is indicated by solid lines. If, as shown in the illustration according to  FIG. 2 , the relay armature  168  moves by way of its end face  206  into the hollow space  236  in the relay housing  156  of the relay  16 , the volume of fluid present in said hollow space will be compressed. The switching pin  177 , which is not illustrated in  FIG. 2  but is illustrated in  FIG. 1 , moves into the armature return  171 , so that the guide bush  202  which is accommodated on said switching pin is moved from the first position  226 , which is illustrated in  FIG. 4  and indicated by solid lines, to its second position  228 , which is indicated by dashed lines. During this movement into the relief space  253 , the openings  230  in the wall of the guide bush  202  are fully or partially exposed, so that a connection is created between the hollow space  236  and the relief space  256  within the relay housing  156 . Depending on the design of the cross sections and the number of openings in the wall of the guide bush  202 , compressed fluid flows out of the hollow space  236  and into the relief space  253 . The contact between the end face  206  of the relay armature  168  and the end face of the armature return  171  is pneumatically damped by virtue of this gradual reduction in pressure in the hollow space  236  and by virtue of compressed fluid flowing out of the hollow space  236  and into the relief space  253  in a controlled manner. 
         [0036]    The illustration according to  FIG. 5  shows a further variant embodiment of a pneumatic damping arrangement of a relay. 
         [0037]    In this variant embodiment, the armature  168 , which is only indicated in  FIG. 5 , is provided with a circumferential slot  238  or a recess over its circumference. In the illustration according to  FIG. 5 , the circumferential slot  238  is approximately square and has a V lip  240  arranged in it. 
         [0038]    The V lip  240  has a limb which engages against the wall of the relay housing  156 . If the relay armature  168  moves in the second movement direction  244 , the upper limb of the V lip  240  will engage against the wall of the relay housing  156 , so that damping in respect of the relay armature  168  is provided in a manner dependent on the movement direction. If, in contrast, the relay armature  168  is moved in the first movement direction  242 , the volume of fluid enclosed in the hollow space  236  will be relieved of pressure. 
         [0039]    The variant embodiments of a pneumatic damping arrangement according to  FIGS. 2 ,  3   4  and  5  can be used to provide direction-dependent pneumatic damping if the relay armature  168  moves, by way of its end face  206 , into the hollow space  236 , the volume of fluid which is contained in said hollow space is compressed, and a gradual reduction in pressure is initiated in the hollow space  236  or, compare the illustration according to  FIG. 5 , the hollow space  236  is sealed off from pressure loss, so that the development of noise when the end face  206  of the relay armature  168  stops against that end face of the armature return  171  which is accommodated in the relay housing  156  in a stationary manner is significantly damped. 
         [0040]    The illustrations according to FIGS.  6  and  6 . 1  show a further variant embodiment of the pneumatic damping arrangement proposed according to the invention. 
         [0041]    If the end face  206  of the armature  168  has reached a distance Δs from the end face of the armature return  171 , a valve element  246  is operated. The valve element  246 , which is in the form of a peg in this case and which is accommodated in a channel  254  such that it can move, is operated by a valve stop  250  stopping against the end of the peg-like valve element  246 . A head  252  of the valve element  246  is moved into the relief space  253  against the action of the spring force of the valve spring  248 , so that a slot  256  is exposed, volumes of fluid flowing out of the hollow space  236  which is defined by the distance Δs and into the relief space  253  via said slot. 
         [0042]    The valve which is illustrated in the illustration according to  FIG. 6  responds only when a well-defined distance Δs between the end face  206  of the relay armature  168  and the end face of the armature return  171 , which is designed to have a geometry which corresponds to said end face of the relay armature, is reached. 
         [0043]    For the sake of completeness, it should be mentioned that reference symbol  150  denotes the pin by means of which power is supplied to the relay  16 . 
         [0044]    The illustration according to  FIG. 6  shows that the slot  256  in the armature return  171  runs, for example, above the actual channel  254  in the material of the armature return  171 . The slot  256  can also be formed at the 3 o&#39;clock, 6 o&#39;clock or 9 o&#39;clock position or any other desired defined position in respect of the illustration according to  FIG. 6.1 . 
         [0045]    The valve element  246  which is illustrated in the illustration according to  FIG. 6  opens only when a well-defined distance Δs between the components relay armature  168  and the armature return  171 , which is arranged in the relay housing  156  in a stationary manner, is reached.