Abstract:
A hybrid motor vehicle power train operating in thermal mode or electric mode includes a thermal engine coupled to a gearbox via a clutch and an electrical machine. The electrical machine is continuously connected to the input shaft of the gearbox.

Description:
BACKGROUND OF THE INVENTION 
     I. Field of the Invention 
     The invention relates to a motor vehicle power train with a hybrid, electric and combustion, drive comprising two drive units, one an electric motor and the other a combustion engine, operating mainly in combustion mode. 
     More specifically, the subject of the invention is a hybrid motor vehicle power train operating in combustion mode or in electric mode, of the type comprising a combustion engine coupled to a gearbox via a clutch, and an electric machine. 
     II. Description of Related Art 
     Various ways of arranging an electric machine in a hybrid power train are known. 
     In one known arrangement, illustrated in particular by the publications FR 2 822 109 and FR 2 837 429, the stator of the electric machine can be fixed to the gearbox housing, itself secured to the housing of the combustion engine, while the rotor is connected to the planet pinion of a planetary gear train. 
     In another known arrangement, in particular that known from publication EP 1 232 890, the electric machine can be placed in a lateral position of the gearbox, the electric machine then being permanently connected to the secondary shaft by a chain and a pair of wheels added to the end of the primary and secondary shafts. 
     The disadvantage with these known arrangements is the additional axial bulk of the power train, which cannot be made compatible with transverse installations without difficulty. 
     BRIEF SUMMARY OF THE INVENTION 
     To overcome this disadvantage, the invention proposes that the electric machine is permanently connected to the primary shaft of the gearbox, preferably by a chain, and offset laterally with respect to the combustion engine. 
     It also proposes that:
         with the vehicle stopped, the combustion engine is started by putting the gearbox in the neutral position and by closing the clutch for coupling the crankshaft and the input shaft of the gearbox, that   with the vehicle running in electric mode, the combustion engine is started by closing the clutch for coupling the crankshaft and the input shaft of the gearbox, that   the power train has a main combustion operating mode, the electric machine then performing the functions of alternator, of motor for applying extra torque at the low speeds of the combustion engine, and of an electric brake when slowing down, that   the power train has an electric operating mode, the clutch for coupling the crankshaft and the input shaft of the gearbox then being open, and the electric machine then being able to propel the vehicle forward in the first and second gear ratios of the gearbox and in reverse by reversing the direction of rotation, in the second gear ratio, and that   the gearbox is robotized.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the invention will become clearly apparent on reading the detailed description given below of an embodiment which does not limit the invention, with reference to the appended drawings, in which: 
         FIG. 1  is an axial overview of the proposed power train, without the combustion engine, and 
         FIG. 2  is a partial cross section thereof. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows the whole of the power train  10 . The combustion engine  20  is represented by way of the nose of the crankshaft, to which is fastened a damping flywheel  30  composed of an actual flywheel  31 , of a vibration damper  32  and of a damping device  33 , corresponding, for example, to publication FR 2 833 329. 
     The combustion engine is coupled via splines  32   a  of the damper to a gearbox  100  which is composed of a clutch and differential housing  110  and of a mechanism housing  120 . The clutch housing comprises a first compartment  111  closed by a flange  112  and containing a conical clutch  113 , the entry cone  114  of which is connected to the damper  32 , like the one disclosed in publication EP 1 318 319. The clutch is opened and closed by way of the bearing  116 . The upper ring  115  of the clutch  113  is connected to the input or primary shaft of the gearbox  100  via a hub  131 . 
     Situated from right to left on the primary shaft  130  are a first fixed drive wheel  132  of the electric machine  200 , a fixed toothing  133  of the first gear ratio, a first freely rotating pinion  134  of the fifth gear ratio, a second freely rotating pinion  135  of the third gear ratio, a third freely rotating pinion  136  of the fourth gear ratio, and a fourth freely rotating pinion  137  of the second gear ratio. These freely rotating pinions can be secured individually with the primary shaft by means of identical coupling devices  138 , for example “conical couplers” of the type proposed by publication FR 2 821 652. The fixed and freely rotating pinions of the primary shaft mesh with a freely rotating pinion and with fixed pinions borne by the secondary shaft  140 , namely, from right to left, a freely rotating pinion  141  of the first gear ratio, a first fixed pinion  142  of the fifth gear ratio, a second fixed pinion  143  of the third gear ratio, a third fixed pinion  144  of the fourth gear ratio, and a fourth fixed pinion  145  of the second gear ratio. 
     The freely rotating pinion  141  of the first gear ratio can be secured with the secondary shaft  140  via a free wheel  146 , according to an arrangement illustrated by publication EP 1 273 825, and via a conventional synchronizing and dog-clutching device  147 . Finally, the secondary shaft bears a fixed toothing  148  for transmitting movement to a conventional differential  150 . 
     The electric machine  200 , borne by the clutch housing  110 , drives a shaft  201  having a single fixed toothing  202  connected to the primary shaft  130  by a chain  203 . 
       FIG. 2  shows the control system and the relative position of the electric machine  200 . The control system is borne by the mechanism housing. This figure is a partial cross section of the gearbox  100  and shows a first electromechanical actuator  210  (as described, for example, in publication EP 1 229 274) in an upper position, the finger  211  of which can cooperate with a first dog sleeve  220  for controlling the coupling devices  138  of the freely rotating pinions  134  and  135  of the third and fifth gear ratios, via a first fork  221 , or with a second dog sleeve  230  for controlling the input clutch  113  via a second fork  231 . 
     The control system comprises a second electromechanical actuator  212 , in a lateral position, the finger  213  of which can cooperate with a dog sleeve  240  for controlling the coupling devices  138  of the freely rotating pinions  136  and  137  of the second and fourth gear ratios, via a fork  241 . Finally, a manual control device  250  allows the finger  251  to cooperate with the dog sleeve  260  for engaging the first and reverse gear ratio, via the fork  252 . 
     According to the invention, the figures show the specific position of the electric machine  200  laterally with respect to the engine and substantially at the usual location of the starter, this arrangement thus not increasing the length of the power train  10 . 
       FIG. 2  shows the compatibility of the control device, of the spindles of the forks  221 ,  231 ,  241  and of the actuators with the connection by the chain  203  of the electric machine  200  and the primary shaft  130  of the gearbox  100 . 
       FIG. 1  shows the absence of a device for reverse operation. The fixed pinion for reversing is advantageously replaced on the primary shaft  130  by the fixed drive wheel  132  of the electric machine  200 . Thus, according to the invention, the drive system of the electric machine, consisting of the wheels  132 ,  202  and of the chain  203 , does not increase the length of the gearbox  100  and, therefore, does not increase the length of the power train  10 . 
     According to the invention, the electric machine is permanently connected to the primary shaft  130  of the gearbox  100 . It is therefore possible to use the electric machine:
         as a starter, provided that the gearbox is in neutral and the clutch  113  is closed,   as an alternator when the vehicle is stopped, provided that the gearbox is in neutral and the clutch  113  is closed,   as a booster when running at whatever gearbox ratio to impart additional torque to the combustion engine at low speeds,   as an energy recovery means for the slowing of the vehicle in any gearbox ratios, apart from the first gear ratio,   in electric drive mode, with the combustion engine rotating or stopped, in reverse operation when reversing the direction of rotation of the electric machine  200  and by using the second gear ratio  137 ,  145  coupled by the device  138  activated by the lateral actuator  212 , since the upper actuator  210  keeps the clutch  113  open in order to disengage the combustion engine  20 ,   in electric drive mode, with the combustion engine rotating or stopped, in forward operation by using the first gear ratio  133 ,  141  or second gear ratio  137 ,  145  coupled by the device  138  activated by the lateral actuator  212 , since the upper actuator  210  keeps the clutch  113  open in order to disengage the combustion engine  20 : the electric machine is thus able to propel the vehicle in forward operation in the first and second gear ratios of the gearbox, and in reverse operation by reversing the direction of rotation, in the second gear ratio, and   in electric drive mode, to start the combustion engine by closing the clutch  113  so as to use the energy of the electric machine or the kinetic energy of the vehicle.