Abstract:
Synchronizer ring made of deep-drawable sheet metal. The ring includes a ring-shaped sheet metal body having a conical section arranged between a wall and a hub surface. One or more radially outwardly projecting guide elements are defined by radially outwardly projecting tapered indentations integrally formed with the ring-shaped sheet metal body. The wall is located at a largest conical diameter side of the ring-shaped sheet metal body and extends substantially perpendicular to a ring body axis. Gear teeth are arranged on a radially outer end of the wall. The one or more guide elements are configured to provide centering guidance relative to a hollow cylindrical surface of a synchronizer ring hub.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 11/891,584, filed Aug. 9, 2007, which claims the priority of European Patent Application No. 06120716.3, filed Sep. 15, 2006, the disclosures of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates to a synchroniser ring for a synchronising device of a shiftable change speed gear transmission as well as to a manual transmission for a vehicle in accordance with the preamble of the independent claims  1  and  10 . 
     In a mechanical, shiftable change speed gear transmission, e.g. in vehicle transmissions, synchroniser rings serve to synchronize the relative speeds which occur between the gear wheel and the gear shaft on a gear change to one another. The synchronisation is achieved by friction between the corresponding friction partners. The function of such transmissions and the process of the synchronisation procedure are known per se and no longer have to be explained in more detail to the person skilled in the art here. 
     It is known for protection against premature wear and/or to improve the friction characteristic to provide the friction surfaces of synchroniser rings with a friction layer, said synchroniser rings being produced as a rule from a metal or a metal alloy such as from brass or steel. Very different types of friction layers are in use in this connection, e.g. thermal injection layers made of molybdenum, carbon friction layers or friction layers made from other materials. 
     A support for a conical synchroniser ring is described in DE 35 19811 A1 which has an outer sprocket ring divided into three and is arranged in a cylindrical hollow space of a synchroniser ring hub, which is also frequently called a synchroniser ring member, and is anchored substantially rotationally fixedly to the synchroniser ring hub via abutments which are formed as lobes. Substantially rotationally fixedly within the context of this application means that, with the exception of small angle excursions in the peripheral direction, the synchroniser ring is rotationally fixedly connected to the synchroniser ring hub. 
     DE 198 53 856 A1 describes a further development of the previously described synchroniser ring, with the synchroniser ring of DE 198 53 856 A1 being characterised in that its width is substantially only determined by the required width of its friction surface. This is achieved in that an abutment, which corresponds to the lobes in accordance with DE 35 19811 A1 in function, is arranged at or close to an end portion of the ring member with a smaller conical diameter and in that the contour of the abutment in the radial direction projects beyond the contour of the outer jacket surface of the ring member. 
     Both synchroniser rings are admittedly basically properly secured by the lobes or abutments against a rotation with respect to the synchroniser ring hub in the operating state, but both lack a reliable guidance in the radial direction in the cylindrical hollow space in the synchronous ring hub. 
     This means the synchroniser rings known from the prior art are admittedly secured against a rotation in the peripheral direction with respect to the synchronous ring hub, but these rings tend increasedly to uncontrolled movements due to their conical outer shape which cooperates with a cylindrical inner contact surface in the cylindrical hollow space of the synchroniser ring hub, e.g. to small radial excursions or tilt movements which can be expressed e.g. in unpleasant vibrations, and thus have a negative effect on the reliability and precision of the synchronisation process, which can result in an increase in the shifting times, in faster and increased wear of the friction surface and of the total synchroniser ring as such, and thus in shorter repair and service intervals, quite apart from the fact that the shifting and driving comfort of a motor vehicle is considerably restricted by the poor guidance of the synchroniser ring in the hollow space of the synchroniser ring hub and the uncontrolled movements resulting therefrom. These effects become all the more significant, the more power or torque has to be shifted by a corresponding transmission. 
     SUMMARY OF THE INVENTION 
     It is therefore the object of the invention to provide an improved synchroniser ring which is guided better in the synchronous ring hub and with which no uncontrolled relative movements occur in the operating state between the synchroniser ring and the synchroniser ring hub during and/or outside the synchronisation process. 
     The subject matters of the invention satisfying these objects are characterised by the features of the independent claims  1  and  10 . 
     The dependent claims relate to particularly advantageous embodiments of the invention. 
     The invention thus relates to a synchroniser ring for a synchronisation device of a shiftable change speed gear transmission including a conical ring member having an inner friction surface and an outer installation surface which each bound the ring member in a radial peripheral direction and extend conically around an axial synchroniser ring axis of the synchroniser ring at a predeterminable friction angle. The ring member is bounded in the axial direction at a largest conical diameter by a gear surface with gear extending substantially perpendicular to the synchroniser ring axis and is bounded at a smallest conical diameter by a hub surface. To fix the synchroniser ring in a cylindrical hollow space of a synchroniser ring hub, a security against rotation is provided which is integrally connected to the ring member and extends from the gear surface of the ring body in the direction of the hub surface. In accordance with the invention, a guide member is provided for the guidance of the installation surface at an inner surface of the cylindrical hollow space at the ring member in a predeterminable region between the gear surface and the hub surface. 
     It is essential for the invention that a guide member is provided for the support or centering and guidance of the installation surface at an inner surface of the cylindrical hollow space of the synchroniser ring hub at the ring member in a predeterminable region between the gear surface and the hub surface, said guide member preferably being provided in the form of a plurality of indentations which are distributed over the installation surface in the peripheral direction. 
     Since securities against rotation are also provided, preferably in the form of security lugs, in addition to the guide members, a synchroniser ring in accordance with the invention is simultaneously exceptionally secured by the securities against rotation against a rotation with respect to the synchroniser ring hub and is simultaneously reliably guided and centered, in particular with respect to the radial direction in the cylindrical hollow space in the synchroniser ring hub. 
     This means that a synchroniser ring in accordance with the invention no longer tends to uncontrolled movements, like the conical synchroniser rings known from the prior art, e.g. to small radial excursions or tilt movements which can e.g. be expressed in unpleasant vibrations, due to its conical outer shape which cooperates with a cylindrical inner contact surface in the cylindrical hollow space of the synchroniser ring hub. The reliability and precision of the synchronisation process is thereby considerably positively influenced by use of a synchroniser ring in accordance with the invention, which can contribute to a reduction in the shifting times, which reduces the wear at the friction surface and of the whole synchroniser ring as such and which thus contributes to longer repair and service intervals, quite apart from the fact that the shifting and driving comfort of a motor vehicle is considerably increased by the exceptional guidance of the synchroniser ring in accordance with the invention in the hollow space of the synchroniser ring hub. These positive effects become all the more effective, the more power or torque has to be shifted by a corresponding transmission. 
     In a specific embodiment, the gear surface is interrupted by a cut-out, in particular by one or two, or three, or more than three cut-outs, and/or the security against rotation is connected to the ring member in the cut-out. 
     Preferably, but not necessarily, just as many securities against rotation are provided as cut-outs in the gear surface. In an embodiment particularly important for practice, precisely three securities against rotation are provided which guarantee a maximum of security against rotation with a minimal construction effort. 
     The security against rotation can in particular be configured as a security lug which extends on the side of the ring member remote from the synchroniser ring axis substantially directed in the same way toward the installation surface. 
     In a very specific embodiment, the security lug can be a security lug having a pocket-like cut-out, whereby an improved anchorage of the synchroniser ring in the synchroniser ring hub can be achieved in the individual case. 
     The number of guide members which can be provided at a synchroniser ring in accordance with the invention preferably lies between two and nine guide members, specifically three guide members, with particularly preferably six guide members being provided, and/or in each case two guide members being arranged at substantially the same interval in the peripheral direction and/or in each case two guide members being arranged between two securities against rotation, whereby a very high degree of radial guidance can be ensured with a minimal construction effort. 
     In an embodiment particularly important for practice, the guide member is made in the form of an indentation of the ring member at the installation surface, said indentation extending radially away outwardly from the synchroniser ring axis. 
     Preferably, a wear reducing and/or a friction optimised friction means, in particular a friction coating, specifically a molybdenum coating and/or a friction layer, in particular a carbon friction layer and/or another friction means is provided on or at the friction surface. 
     In construction terms, the synchroniser ring is a shaped sheet metal part manufactured from a deep-drawable metal sheet and/or is made from a steel, preferably from C55, C80 or C80M steel, in particular from C35 or C45 steel. 
     In other embodiments, there is provided a synchronizer ring made of deep-drawable sheet metal, comprising a ring-shaped sheet metal body having a conical section arranged between a wall and a hub surface. The conical section has a conical inner friction surface and a conical outer installation surface. One or more radially outwardly projecting indentations are integrally formed with the ring-shaped sheet metal body and functioning as one or more guide elements. The wall is located at a largest conical diameter side of the ring-shaped sheet metal body and extends substantially perpendicular to a ring body axis. Gear teeth are arranged on a radially outer end of the wall. The one or more guide elements are arranged between the conical section and the hub surface. The one or more guide elements are configured to provide centering guidance relative to a hollow cylindrical surface of a synchronizer ring hub, whereby the ring-shaped sheet metal body is centered with respect to the synchronizer ring hub when a hub surface end of the ring-shaped sheet metal body is slid into the synchronizer ring hub. One or more anti-rotation members project or extend from the largest conical diameter side of the ring-shaped sheet metal body toward a direction of the hub surface. The one or more anti-rotation members are adapted to extend into a respective opening arranged in the synchronizer ring hub. 
     The ring-shaped sheet metal body may be a one-piece member. The one or more guide elements may comprise plural equally spaced integrally formed guide elements. The one or more anti-rotation members may comprise plural equally spaced and/or integrally formed anti-rotation members. The synchronizer ring may be arranged on a synchronising device of a shiftable change speed gear transmission. The wall may comprise one or more cut-outs or sections that lack gear teeth. One of the one or more anti-rotation members may be arranged in one of the one or more cut-outs or sections that lack gear teeth. 
     Each of the anti-rotation members may be a lug that one of extends into a slot-shaped opening arranged in the synchronizer ring hub and is oriented substantially parallel to the ring member axis. Each of the anti-rotation members is arranged in one of a cut-out or a section of the wall that lack gear teeth. The one or more anti-rotation members may comprise three anti-rotation members and each is arranged in one of three cut-outs or sections of the wall that lack gear teeth. At least one of the anti-rotation members may be a lug having a recess. The one or more guide elements may comprise between two and nine guide elements. The one or more guide elements may comprise between two and nine integrally formed and equally spaced guide elements. 
     The conical inner friction surface may comprise one of a wear-reducing coating, a friction coating or layer, a molybdenum coating and/or a carbon friction layer. 
     The deep-drawable sheet metal is at least one of steel, C55, C80 or C80M steel and C35 or C45 steel. 
     The invention also provides for a manual transmission for a vehicle comprising the synchronizer ring described above. 
     The invention also provides for a synchronizer ring made of deep-drawable sheet metal, comprising a sheet metal ring body having a conical section arranged between a wall and a hub end. The conical section has a conical inner friction surface and a conical outer installation surface. Plural radially outwardly projecting indentations are integrally formed with the conical section and functioning as centering guide elements. The wall is located at a largest conical diameter side of the ring body and extending substantially perpendicular to a ring axis. Gear teeth are arranged on a radially outer end of the wall. Plural centering guide elements extend to the hub end. Each centering guide element comprises at least one of converging outer edges which converge toward one another as the approach a radially outer edge and a rounded radially outer edge. The centering guide elements are configured to provide centering guidance relative to a hollow cylindrical surface of a synchronizer ring hub, whereby the ring body is centered with respect to the synchronizer ring hub when the hub end of the ring body is slid into the synchronizer ring hub. Plural integrally formed anti-rotation members project or extend toward a direction of the hub. The plural anti-rotation members are configured to extend into openings arranged in the synchronizer ring hub when the hub end of the ring body is slid into the synchronizer ring hub. 
     The invention also provides for a synchronizer device comprising a sheet metal ring member having an integrally formed conical section arranged between an integrally formed wall with a gear and a hub end. The conical section has a conical inner surface and a conical outer surface that is substantially parallel to the conical inner surface. Plural radially outwardly projecting are integrally formed indentations functioning as centering guide elements. The wall with the gear is located at a largest conical diameter side of the ring member and extending substantially perpendicular to a ring member axis. Plural integrally formed guide elements extend to the hub end and having radially outer rounded edges. A synchronizer ring hub comprises an inner cylindrical surface and anti-rotation openings. The guide elements are configured to provide centering guidance relative to the cylindrical surface of the synchronizer ring hub, wherein the ring member is centered with respect to the synchronizer ring hub when the hub end of the ring member is slid into the synchronizer ring hub. Plural integrally formed anti-rotation members project or extend toward a direction of the hub. Each anti-rotation member extends into a respective anti-rotation opening arranged in the synchronizer ring hub when the hub end of the ring member is slid into the synchronizer ring hub. 
     The one or more guide elements may comprise a rounded or outwardly curved radially outer edge. The one or more anti-rotation members may have ends that face in a direction parallel to the ring body axis and are integrally formed. The one or more guide elements may comprise at least one of converging outer edges which converge toward one another as the approach a radially outer edge and a rounded radially outer edge. The one or more guide elements may comprise a radially outermost edge and a radially innermost edge axially spaced from the wall by a lesser amount that the radially outermost edge. The one or more guide elements may comprise a radially outermost edge and a radially outer edge located where the one or more guide elements meets the conical outer installation surface, wherein the radially outer edge is axially spaced from the wall by a lesser amount that the radially outermost edge. 
     The invention further relates to a manual transmission for a vehicle, in particular for a passenger car, a transporter or a truck, including a synchroniser ring in accordance with one of the preceding claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be explained in more detail in the following with reference to the schematic drawing. There are shown: 
         FIG. 1  is an embodiment of a synchroniser ring in accordance with the invention in section; 
         FIG. 2  is a side view of a synchroniser ring in accordance with  FIG. 1  in the installed state; 
         FIG. 3  is another view in accordance with  FIG. 2 ; 
         FIG. 4  is a security lug having a pocket-like cut-out. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows, in a schematic representation in section, an embodiment of a synchroniser ring in accordance with the invention which is designated as a whole in the following by the reference numeral  1 . The same reference numerals in the different Figures designate technically equivalent features or relate to features with a technically equivalent function. 
     The synchroniser ring  1  of  FIG. 1  includes a conical ring member  3  having an inner friction surface  4  with a carbon friction layer  41  and an outer installation surface  5  which respectively bound the ring member  3  in a radial peripheral direction in a manner known per se. The outer installation surface  5  and the inner friction surface  4  extend substantially parallel to one another at a predeterminable friction angle α, which cannot be seen in  FIG. 1 , conically around an axial synchroniser ring axis  6  of the synchroniser ring  1 . 
     The ring member  3  is bounded in the axial direction at a largest conical diameter d  1  by a gear surface  7  with gear  71  extending substantially perpendicular to the synchroniser ring axis  6  and is bounded at a smallest conical diameter d 2  by a hub surface  8 . To fix the synchroniser ring  1  in a cylindrical hollow space  9  of a synchroniser ring hub  10 , which is not shown in  FIG. 1 , a security against rotation  11  is provided which is integrally connected to the ring member  3  and extends from the gear surface  7  of the ring member  3  in the direction towards the hub surface  8 , a construction such as is in principle already known from the prior art. The security against rotation  11  in accordance with  FIG. 1  is a security lug  111  which can be formed, for example, on the manufacture of the synchroniser ring  1  by bending over a portion initially projecting radially outwardly from the ring member  3  in the direction towards the installation surface  5 . 
     This means the security against rotation  11 , which is made as a security lug  111 , extends on the side of the ring member  3  remote from the synchroniser ring axis  6  substantially directed in the same way to the installation surface  5 . 
     As will be explained even more precisely later with reference to the following Figures, the security lug  111  is configured and is arranged with respect to the installation surface such that the security lug  111  can be anchored in a corresponding cut-out  101  of the synchroniser ring hub  10  in the installed state. 
     In accordance with the invention, a guide member  12  is provided for the guidance of the installation surface  5  at an inner surface  91  of the cylindrical hollow space  9  of the synchroniser ring hub  10 , which is, as stated, not shown in  FIG. 1  because  FIG. 1  does not show the synchroniser ring  1  in the installed state, in a predeterminable region between the gear surface  7  and the hub surface  8 , said guide member being configured in the embodiment of  FIG. 1  and  FIG. 2  of enormous importance for practice in the form of an indentation  12   b  defining the guide member  12  of the ring member  3  at the installation surface  5 , with the indentation  12   b  extending radially away outwardly from the synchroniser ring axis  6 . In addition to the indentation  12   b  defining the guide member  12 , the guide member  12  also includes a rounded edge  12   a  that is formed by converging outer edges  12   d  extending to a radially outermost edge  12   c . As can be seen in  FIG. 2 , an radially innermost edge  12   e  is axially spaced from the wall  7  by a lesser amount than the radially outermost edge  12   c.    
     In the installed state of the synchroniser ring  1 , the indentations  12   b  in accordance with the invention then center and guide the synchroniser ring  1  securely and reliably in the cylindrical hollow space  9  provided in the synchroniser ring hub  10  for the reception of the installation surface  5 . 
     In  FIG. 2 , a side cross-section view of a synchroniser ring  1  in accordance with  FIG. 1  is shown schematically in the installed state. As should be apparent from  FIG. 2 , the indentations  12   b  are tapered in the radially inward direction. The section has been selected along the arrow A in accordance with  FIG. 3  just such that the security lug  111  cannot be seen. 
     The conical ring member  3  with its inner friction surface  4 , which has a carbon friction layer  41  in the present example as shown in  FIGS. 1 and 2 , , and the outer installation surface  5  extend conically and substantially parallel to one another at the friction angle α around the axial synchroniser ring axis  6  of the synchroniser ring  1 . 
     The synchroniser ring  1  is supported in a centered fashion with the installation surface  5  in the hollow space  9  of the synchroniser ring hub  10  by the guide elements  12  in accordance with the invention, which are defined by indentations  12   b.    
     The gear surface  7  with gear  71  is located in a manner known per se outside the synchroniser ring hub  10  such that the gear  71  can enter into rotationally fixed engagement with a further gear not shown in  FIG. 2  of a shiftable change speed gear transmission likewise not shown. 
     In  FIG. 3 , finally, the synchroniser ring of  FIG. 1  can again be seen from a direction B in accordance with  FIG. 2  in a section along and at the point C, such as is designated more closely by the arrow C in  FIG. 2 . 
     It can be seen particularly easily in  FIG. 3  how the security against rotation  11 , which is integrally connected to the ring member  3  and extends from the gear surface  7  of the ring member  3  in the direction towards the hub surface  8  is anchored in the cut-out  101  of the synchroniser ring hub  10  for the fixing of the synchroniser ring  1  in the cylindrical hollow space  9  of the synchroniser ring hub  10  and, as already mentioned, is a security lug  111 . The synchroniser ring  1  is reliably secured against rotation around the synchroniser ring axis  6 , with the exception of small angles, by the anchorage of the security lug  111  in the cut-out  101  of the synchroniser ring hub  10 . For technical reasons, however, which are sufficiently known to the person skilled in the art, small rotational movements of the synchroniser ring  1  are preferably to be allowed around the synchroniser ring axis  6 . This is achieved in that the cut-outs  101  are somewhat wider in the peripheral direction than the security lugs  111 . 
     In  FIG. 4 , finally, another specific embodiment of the present invention is shown in a schematic manner, with the security against rotation  11  being a security lug  111  which is configured as a security lug  1110  having pocket-like cut-outs such that they can be anchored in a corresponding cut-out of another synchroniser ring hub  10 , with the cut-outs for the anchorage of the security lugs  1110  of the other synchroniser ring hub  10  then being formed correspondingly, e.g. in two parts with a center web, whereby a better fixing of the synchroniser ring  1  to the synchroniser ring hub  10  is possible in specific cases. 
     It is understood that all the embodiments explicitly discussed in this application are only to be understood as exemplary for the invention and in particular all suitable combinations which can advantageously be used for specific applications or all further developments obvious to the skilled person are also covered by the invention.