Abstract:
A change-speed transmission for motor vehicles, in particular manual transmission, having a plurality of forward gears and, optionally, one reverse gear, includes at least one input shaft, an output shaft and, optionally, a layshaft, between which the idler gears, which can be shifted via synchronous clutches, and the fixed gears of the gearwheel sets are arranged. At least one of the has a two-part design and is mounted in the transmission housing with mutually different axes of rotation, an annular gear stage is functionally provided between the sub-shafts and includes a internally-toothed annular gear and an externally-toothed spur gear that meshes therewith, the sub-shaft which has the larger axial distance to the other shaft bearing gearwheels of the lower forward gears and, optionally, of the reverse gear.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is the U.S. National Stage of International Application No. PCT/EP2013/002991, filed Oct. 4, 2013, which designated the United States and has been published as International Publication No. WO 2014/063779 and which claims the priority of German Patent Application, Serial No. 10 2012 020 884.7, filed Oct. 24, 2012, pursuant to 35 U.S.C. 119(a)-(d). 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a change-speed transmission for motor vehicles, in particular a manual transmission. 
     U.S. Pat. No. 1,987,879 discloses a manual transmission with two forward gears in which a ring gear stage is used for achieving different transmission ratios. Hereby a gear wheel on a layshaft outputs directly onto the externally splined ring gear, or onto a further gear wheel on the layshaft via an axially offset shaft onto a gear wheel, and this gear wheel via the shaft onto a spur gear, which meshes with an internal spline of the ring gear. The resulting design of the transmission is relatively complicated and hardly feasible for transmissions with more than two forward gears and optional reverse gear. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to propose a change-speed transmission of the generic type, which has a relatively simple construction while enabling greater constructive freedom, in particular regarding the achievable spacing of the transmission ratios. 
     The object is solved with the features set forth in the independent patent claim. Advantageous refinements and embodiments of the invention are the subject matter of the dependent claims. 
     According to the invention it is proposed that at least one of the shafts is configured two-part and is supported in the transmission housing with different rotation axes, in that a ring gear stage with an internally splined ring gear and an externally splined spur gear which meshes with the ring gear is functionally provided between the subshafts, wherein the subshaft with the greater axial distance to the other shaft carries gear wheels of the lower forward gears and optionally of the reverse gear. The ring gear stage thus already has an influence on the transmission ratios for multiple gears arranged in force flow upstream or downstream and also enables a greater axial distance of the corresponding subshaft to the neighboring shaft resulting in an improved accommodation of larger gear sets which enable lower transmission ratios. This enables beside a simpler, compact transmission design for example in the case of six forward gears and a reverse gear, a spacing in the transmission ratios of 6 or more. 
     The ring gear can advantageously be provided on the input shaft or on the output shaft between the gear sets of the higher forward gears and the gear sets of the lower gears. 
     In an alternative, advantageous embodiment of the invention the ring gear can be arranged between the continuous input shaft or the continuous output shaft and a reverse driving ring gear, wherein the ring gear again has a greater axial distance to the output shaft and carries the gear wheels of the lower gear sets. 
     In a particularly preferred refinement, the drive connection can be interrupted on the ring gear stage via a shiftable clutch. In particular when the ring gear stage is arranged together with the shiftable clutch on the input shaft and the idler gear wheels of the corresponding lower gear sets are positioned on the output shaft, this enables a partial switching off of the transmission elements with the advantage of a particularly good efficiency of the transmission in the higher forward gears, wherein the gear sets of the lower forward gears and optionally the reverse gear stand still, i.e., do not generate any transmission losses. 
     In a motor vehicle with four-wheel drive the ring gear stage can also be arranged on the input shaft and the output shaft can be a hollow shaft, through which an output shaft of the integrated interaxial differential extends, wherein the output shaft outputs onto the differential housing of the interaxial differential and the one output shaft outputs onto an opposing axial differential. This solution is particularly advantageous for the transverse mounting of a drive aggregate as well as for the longitudinal mounting, wherein only the final drive has to be correspondingly adjusted (bevel gear drive or spur wheel drive, etc.) 
     In a so-called standard drive, in which the input shaft and the output shaft are arranged coaxial, it is proposed that the ring gear stage is arranged on the layshaft, which carries the gear wheels, which significantly simplifies the construction of the transmission (in contrast to the aforementioned known construction). 
     In an advantageous refinement of the invention, for example for automatically shifted change-speed transmissions, the ring gear stage can at the same time be configured as gear wheel pump or crescent pump for delivering lubricant oil or hydraulic oil. With this the ring gear stage can serve an additional function given a corresponding configuration of the housing (suction and pressure chambers), integrated channels), which removes the requirement for a separate delivery pump to supply the transmission control, which is advantageous in terms of construction and manufacture. 
     Finally in a further advantageous application the ring gear can be arranged on the output shaft and additionally have an external spline, which in connection with a pawl, which is provided pivotal in the housing, forms a parking lock or an output stage of the transmission. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       In the following multiple exemplary embodiments of the invention are explained in more detail by way of the included block diagrams. 
       It is shown in: 
         FIG. 1  a transmission for motor vehicles with six forward gears and a reverse gear, whose gear sets are arranged on an input shaft and an output shaft, and with a ring gear stage on the two-part input shaft, which is provided between lower and higher gear sets; 
         FIG. 2  the manual transmission according to  FIG. 1 , in which the ring gear stage is arranged on a two-part output shaft; 
         FIG. 3  a manual transmission according to  FIG. 1  in which the ring gear stage is provided between a continuous input shaft and a reversed riving hollow shaft, which carries gear wheels of the lower gear wheel sets; 
         FIG. 4  a manual transmission according to  FIG. 1  in which the ring gear stage is arranged between a continuous output shaft and a hollow shaft, which carries the gear wheels of the lower gear wheel set; 
         FIG. 5  a manual transmission according to  FIG. 3  in which the ring gear stage has a switching clutch by means of which the corresponding hollow shaft is switchable; 
         FIG. 6  a manual transmission for a four wheel drive motor vehicle with a ring gear sage on the input shaft, an output shaft configured as hollow shaft, which outputs onto an integrated interaxle differential, whose output shafts are drivingly connected with a front axle differential and a rear axle differential; 
         FIG. 7  a manual transmission according to  FIG. 3 , in which the ring gear stage which is arranged on the input shaft is also configured a gearwheel pump for supplying hydraulic fluid for a transmission control; and 
         FIG. 8  a further manual transmission for motor vehicles with an input shaft, a coaxial output shaft and an axially parallel layshaft, which is configured two-part and is drivingly connected via a ring gear stage. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1  shows as block diagram and a change-speed transmission or manual transmission  10  for motor vehicles without transmission housing, with an input shaft  14  which can be connected with a drive aggregate (not shown) via a separating clutch  12 , and an output shaft  16 . 
     Between the shafts  14 ,  16  meshing gear wheels of gear sets for six forward gears 1 to 6 and a reverse gear R are arranged. The idler gear wheels of the gear sets 1 to 6 and of the reverse gear R are shiftable in a known manner via only schematically indicated synchronous clutches  18  and can thus be connected with the corresponding fixed gear wheel on the respective other shaft  14 ,  16 . 
     The two-part input shaft  14  of the transmission  10  is connected via a ring gear stage  20  with a ring gear  20   a , which has a greater diameter and internal spline, and with a spur gear wheel  20   b , which is in engagement with the ring gear  20   a , wherein the subshaft  14   a  which carries the spur gear wheel  20   b , carries the gear wheels of the gear sets 3 to 6 and the subshaft, which is connected with the ring gear  20   a , carries gear wheels of the gear sets 1, 2 and R. 
     While the continuous, one-part drive shaft  16  is supported rotatable in the transmission housing via a first rotation axis, the rotation axes of the subshafts  14   a ,  14   b  of the input shaft  14 , which are axially parallel thereto, are offset relative to each other with an axial offset of a few millimeters, as can be seen. Hereby the subshaft  14   b , which carries the ring gear  20   a , has a greater distance Δa 1  to the output shaft  16   b  than the subshaft  14   a  which is arranged with a smaller axial distance Δa 2 . 
     As a result of the configuration of the ring gear stage  20  (diameter, number of teeth) the desired axial offset Δ v  and the transmission ratio of the ring gear stage  20  can be defined. The axial offset Δ v  also enables greater constructive freedom regarding the configuration of the transmission ratio and the accommodation of the lower forward gears 1, 2, which are situated on the subshaft  14   b , and optionally the reverse gear R. 
       FIGS. 2 to 8  show alternative exemplary embodiments of the invention, which in order to avoid repetition, are only described insofar as they significantly differ from the exemplary embodiment of  FIG. 1 . Functionally same parts are provided with the same reference signs. 
     According to  FIG. 2  the ring gear stage  20  is arranged on the output shaft  16  of the transmission  10 . 
     For this the output shaft  16  is constructed two-part with a subshaft  16   a  and a subshaft  16   b  with the ring gear stage  20  arranged there between. On the subshaft  16   a , which has a greater axial distance a1 to the one-part input shaft  14 , the spur gear wheel  20   b  and the gear wheels of the lower gear sets 1, 2 and R are arranged, while the second subshaft  16   b  carries the gear wheels of the higher gear sets 3 to 6. 
       FIG. 3  shows an alternative configuration of the two-part input shaft  14  of the transmission  10  compared to  FIG. 1 , in which the ring gear stage  20  is arranged on a front side end of the input shaft  14  or on the continuous subshaft  14   a  and on a reverse driving hollow shaft  14   b  as second subshaft or respectively drivingly connects the latter. 
     The hollow shaft  14   b , which has a greater distance a1 to the output shaft  16 , carries the ring gear  20   a  and the gear wheels of the lower gear sets 1, 2 and R, while the first subshaft  14   a  is drivingly connected with the spur gear wheel  20   b  of the ring gear stage  20  and the gear wheels of the higher gear sets 3 to 6. 
     In the exemplary embodiment according to  FIG. 4  the ring gear stage  20  is provided on the one front side end of the two-part output shaft  16 . 
     For this the output shaft  16  has a continuous subshaft  16   a  and a reverse driving hollow shaft  16   b , which are drivingly connected with each other by means of the ring gear stage  20 . 
     The subshaft  16   a  carries hereby a ring gear  20   a  and the gear wheels of the lower gear sets 1, 2, R, and has correspondingly a greater axial distance a1 to the one-piece input shaft  14  than the hollow shaft  16   b  with the spur gear wheel  20   b  and the gear wheels of the higher gear sets 3 to 6. 
     In contrast to the ring gear stages  20  described above, the ring gear  20   c  is additionally provided with an external spline which in cooperation with a pawl (not shown), which is pivotally arranged in the transmission housing forms a parking lock P. When the pawl is retracted, the ring gear  20   c , and with this the outputting subshaft  16   a  in the transmission housing of the transmission, is blocked. Optionally the external spline can also be used as output stage. 
       FIG. 5  shows an alternative exemplary embodiment to  FIG. 3 , in which the driving connection can be interrupted via the ring gear stage  20  on the input shaft  14  of the transmission  10  by means of a shifting clutch  22  (this can for example be a synchronous clutch  18  common in transmissions. 
     When the shifting clutch  22  is engaged, the spur gear wheel  20   b  of the ring gear stage  20  is coupled with the continuous subshaft  14   a , while it can freely rotate on the subshaft  14   a , when the switching clutch  22  is disengaged. 
     The gear wheels situated on the hollow shaft  14   b  of the lower gear sets 1, 2, R are fixed gear wheels, which are in engagement with idler gear wheels on the output shaft  16 , which idler gear wheels can be shifted via synchronous clutches  18 . 
     While the arrangement fixed gear wheels—idler gear heels of the gear sets 1 to 6 and R on the input shaft  14  and the output shaft  16  in the exemplary embodiments can be configured by constructive considerations, it is a characterizing feature of the embodiment of  FIG. 5  that the fixed gear wheels of the gear sets 1, 2 and R are positioned on the hollow shaft  14   b . As a result all gear wheels of the gear sets 1, 2 and R stand still when the hollow shaft  14   b  is decoupled in the higher gears 3 to 6, i.e., they do not cause drive losses or wear. 
       FIG. 6  shows a further exemplary embodiment of the invention with a transmission  24  for all-wheel drive motor vehicles, in which the output shaft  16  is configured as hollow shaft, on which the gear wheels of the gear sets 1 to 6 are arranged. 
     The input shaft  14  is again constructed two-part with a subshaft  14   a  and a hollow shaft  14   b , which are interconnected via the ring gear stage  20  as described above. 
     The output shaft  16  outputs onto the differential housing  26  of an interaxle differential  28  which is integrated in the transmission housing, and whose one output shaft  30  drives a front axle differential  36  of the motor vehicle via a spur gear drive  34 , while the second output shaft  32  outputs onto the rear axle of the motor vehicle in a not further shown manner. 
     The shown transmission  24  may be used for the longitudinal mounting as well as for a transverse mounting in the motor vehicle. The same applies to the transmissions  10  described above. 
     In the transmission  10  according to  FIG. 7  the ring gear stage  20  is arranged on the free end side of the input shaft  14  or the hollow shaft  14   b.    
     Beside these functions as transmission stage, the ring stage  20  is also configured in cooperation with housing elements of the transmission  10  as gearwheel crescent pump, which aspirates hydraulic fluid, for example gear oil, form an oil sump  38  as indicated with arrows, and supplies the hydraulic fluid under pressure to a not shown electro-hydraulic transmission control. The crescent pump can be of known construction with a suction pressure chamber formed in the housing and correspondingly provided suction and supply channels. 
       FIG. 8  shows a transmission  40  with an input shaft  42 , a coaxial output shaft  44  and an axially parallel layshaft  46 , wherein the layshaft  46  is configured two-part and has the ring gear stage  20  with the shifting clutch  22 . 
     The layshaft  46  includes a subshaft  46   a  and a reverse driving hollow shaft  46   b , which are interconnected via the ring gear stage  20  as described above. 
     Beside the gear wheels of the gear sets 3, 4, 6 or 1, 2, R arranged between the output shaft  44  and the layshaft  46 , a fixed (not switchable) gear set  48  is provided on the input shaft  42  and the layshaft  46   a , via which gear set  48  the layshaft  46  is constantly driven. 
     Further, beside the forward drive  6  a direct drive, for example as forward gear  5 , can be shifted via the synchronous clutch  18  provided between the input shaft  42  and the output shaft  44 , in which the input shaft  42  and the output shaft  44  are directly connected with each other. 
     Driven via the gear wheel set  48 , the forward gears 3, 4, 6 can be shifted, or respectively driven via the ring gear stage  20 , the forward gears 1, 2 and the reverse gear R can be shifted as described above. In addition the gear sets of the forward gears 1, 2 and of the reverse gear R can be turned off by means of the shifting clutch  22 , when driving in the higher forward gears 3 to 6.