Patent Publication Number: US-2023139342-A1

Title: Axle for a vehicle

Description:
TECHNICAL FIELD 
     The invention relates to an improved axle for a vehicle, and more particularly to an axle for an electric vehicle or a hybrid vehicle. 
     A vehicle generally comprises two axles, respectively a front axle and a rear axle, each connected to wheels. In some embodiments, a vehicle may include one or more front and/or rear axle(s). Each axle can alternatively be none driven or driven axle(s). 
     A driven axle comprises a powertrain arranged to provide torque to the wheels. The driven axle can be an electric axle (E-axle) which comprises at least an electric motor and a transmission unit. An E-Axle is a compact and economical electric drive solution for Battery Electric Vehicles (BEV), Fuel Cells Electric Vehicles (FCEV) and hybrid vehicles. 
     The invention can be applied in low-duty, medium-duty and heavy-duty vehicles, such as trucks, buses and construction equipment, as well as in passenger cars. Although the invention will be described with respect to a truck, the invention is not restricted to this particular vehicle type, but may also be used in other vehicles. 
     BACKGROUND 
     The transport industry is constantly looking for environmental and safety improvements. To this effect, it is known to provide auxiliary brakes as a supplement to the service brakes of the vehicle. This is typically done in order to increase the life time of the service brakes and to increase the available braking force, since these are otherwise exposed to significant wear due to the heavy loads on the vehicle, especially when driving down steep gradients, the vehicle has to be slowed down before developing a too high speed. 
     Retarders are examples of auxiliary brakes. A retarder is usually of the hydrodynamic retarder or electromagnetic retarder type. These are arranged on powertrains, after the main gearbox of the vehicle and its clutch device. As the retarder is arranged after the clutch device of the vehicle, it can brake the vehicle even when the clutch is disengaged or when the gearbox is in neutral position. 
     However, the presence of a retarder on a powertrain leads to space problems. Indeed, the integration of a retarder on a powertrain is space consuming. 
     Moreover, the transport industry is currently in a process of transition to electro-mobility, which implies the use of electric power to drive vehicles. Electro-mobility is mainly developed to meet increasingly stringent emission regulation requirements and the banning of internal combustion engine vehicles by some cities. 
     Battery Electric Vehicles (BEV) and Fuel Cells Electric Vehicles (FCEV) generally comprise a regenerative braking system, which allow to decelerate the vehicle without using the service brakes to cope with legal and customer demands. This is only valid when the battery system is able to accept the electric energy created during braking event by the electric motor(s) of the powertrain. During regenerative braking, the kinetic energy of the wheels during deceleration phases is converted into electrical energy using the motor(s) as a generator. This electrical energy is used to charge the battery system. When the battery system is full of energy, it cannot accept any electrical energy without being damaged. Thus, the addition of a retarder will solve this issue since the retarder can be used when the battery system is full, and more generally when needed in complement to the regenerative braking system. 
     In order to free as much space as possible for batteries, chassis and other large parts, such as aerodynamic profiles, powertrains must be as compact as possible. 
     SUMMARY 
     An object of the invention is to provide an auxiliary brake for a vehicle, which auxiliary brake is not space consuming. 
     The object is achieved by an axle for connecting two wheels of a vehicle, characterized in that the axle comprises a retarder configured to generate a braking force. 
     By the provision of an axle, which comprises a retarder, the service brakes of the vehicle are supplemented without consuming space on the powertrain. 
     According to one embodiment, the axle is a driven axle comprising a transmission unit comprising:
     An electric motor;   A gearbox comprising:
       A primary shaft connected to the electric motor;   An output shaft parallel to the primary shaft, the output shaft comprising a first output gear, a second output gear and a third output gear;   An intermediate shaft parallel to the primary shaft, the intermediate shaft comprising:
           a first intermediate gear connected to the primary shaft and to the first output gear,   a second intermediate gear connected to the second output gear, and   a third intermediate gear connected to the third output gear; and   
           A differential assembly connected to the output shaft.   
       

     According to one embodiment, the retarder is connected to the output shaft or to the intermediate shaft. 
     According to one embodiment, wherein the retarder is connected to the output shaft or to the intermediate shaft via a transmission shaft. 
     According to one embodiment, the retarder is mounted at a distal end of the output shaft or intermediate shaft, relative to the differential assembly. 
     According to one embodiment, the retarder is connected to the second or third output gear. 
     According to one embodiment, the retarder is connected to a proximal end of the intermediate shaft relative to the differential assembly. 
     According to one embodiment, the axle comprises two electric motors, and the gearbox comprises a primary shaft and an intermediate shaft for each electric motor. 
     According to one embodiment, the axle is a non-driven axle, the retarder being a wheel driven retarder. 
     According to one embodiment, the axle comprises a differential assembly and two shafts, each shaft being connected to the differential assembly and to a wheel, the retarder being connected to the differential assembly. 
     According to one embodiment, wherein the axle comprises two retarders. 
     According to one embodiment, the axle is a driven axle. 
     According to a further embodiment, the axle is a non-driven axle. 
     A further object of the invention is a vehicle comprising an axle as described above. 
     Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples. 
       In the drawings: 
         FIG.  1    is a perspective view of a vehicle, comprising an axle according to the invention, 
         FIG.  2    is a schematic view of an axle according to a first embodiment of the invention, 
         FIG.  3    is a schematic view of an axle according to a second embodiment of the invention, 
         FIG.  4    is a schematic view of an axle according to a third embodiment of the invention, 
         FIG.  5    is a schematic view of an axle according to a fourth embodiment of the invention, 
         FIG.  6    is a schematic view of an axle according to a fifth embodiment of the invention, 
         FIG.  7    is a schematic view of an axle according to a sixth embodiment of the invention, 
         FIG.  8    is a schematic view of an axle according to a seventh embodiment of the invention, 
         FIG.  9    is a schematic view of an axle according to an eighth embodiment of the invention, 
         FIG.  10    is a schematic view of an axle according to a ninth embodiment of the invention, 
         FIG.  11    is a schematic view of an axle according to a tenth embodiment of the invention, 
         FIG.  12    is a schematic view of an axle according to an eleventh embodiment of the invention, 
         FIG.  13    is a schematic view of an axle according to a twelfth embodiment of the invention, 
         FIG.  14    is a schematic view of an axle according to a thirteenth embodiment of the invention, 
         FIG.  15    is a schematic view of an axle according to a fourteenth embodiment of the invention, 
         FIG.  16    is a schematic view of an axle according to a fifteenth embodiment of the invention, 
         FIG.  17    is a schematic view of an axle according to a sixteenth embodiment of the invention, 
         FIG.  18    is a schematic view of an axle according to a seventeenth embodiment of the invention, and    
     
    
    
     DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION 
       FIG.  1    shows a vehicle  1 , comprising two axles  10 , respectively a front axle and a rear axle, each connected to wheels  2 . The vehicle  1  can be an electric, fuel cell or hybrid vehicle, i.e. a vehicle using electric energy as a source of power. In the example, the vehicle is a truck. 
     In an alternative embodiment, the vehicle may include one or more front and/or rear axle(s). Each axle can alternatively be none driven or driven axle(s). 
     The present description is given in an X, Y, Z referential where X is defined as the longitudinal direction of the vehicle  1 , Y is defined as the transversal direction and Z is defined as the vertical direction of the vehicle  1 . 
       FIGS.  2  to  18    show an axle  10  for connecting two drive wheels  2  or two non driven wheels  2 ′ of a vehicle  1  ( FIG.  1   ). The axle  10  comprises a retarder  12  configured to generate a braking force. 
     As illustrated in  FIGS.  2  to  13  and  17   , the axle  10  can be a driven axle. The axle  10  can comprise a transmission unit  14  comprising:
     An electric motor EM 1 ;   A gearbox  16 ; and   A differential assembly  18 .   

     The electric motor EM 1  can be on one side of the differential assembly  18  and the gearbox  16  on the other side, opposite to the electric motor EM 1 . 
     The retarder can be axle driven or wheel driven. 
     The gearbox  16  is configured to connect the electric motor EM 1  to the differential assembly  18 . The differential assembly  18  can comprise a bevel set crown wheel  45  connected to the gearbox  16 . 
     As illustrated in  FIGS.  2  to  13   , the gearbox  16  can comprise:
     A primary shaft  20  connected to the electric motor EM 1 ;   An output shaft  22  parallel to the primary shaft  20  and connected to the differential assembly  18 ; and   An intermediate shaft  24  parallel to the primary shaft  20 .   

     More precisely, the output shaft  22  can comprise a first output gear  26 , a second output gear  28  and a third output gear  30 . The intermediate shaft  24  can comprise a first intermediate gear  32 , a second intermediate gear  34 , and a third intermediate gear  36 . The primary shaft  20  can comprise a gear  38 . The first intermediate gear  32  can be connected to the gear  38  of the primary shaft  20 , and to the first output gear  26  of the output shaft  22 . 
     The second intermediate gear  34  can be connected to the second output gear  28 , and the third intermediate gear  36  can be connected to the third output gear  30 . 
     Typically, the gear  38  can be fixed in rotation with the primary shaft  20 . For example, the gear  38  can be integral with the primary shaft  20 , meaning that the gear  38  and the primary shaft  20  form a unique part. 
     The intermediate shaft  24  can have a first extremity E 1  and a second extremity E 2 . The first intermediate gear  32  can be located at the first extremity E 1  of the intermediate shaft  24 . The output shaft  22  can have a first extremity E 11  and a second extremity E 12 . The first output gear  26  can be located at the first extremity E 11  of the output shaft  22 . The first extremity E 1  of the intermediate shaft  24  and the first extremity E 11  of the output shaft  22  can be proximal to the differential assembly  18 , and more precisely to the bevel set crown wheel  45 . 
     As shown in  FIGS.  2  to  13  and  17   , the axle  10  can comprise two drive shafts  40 . Each drive shaft  40  can be connected to the differential assembly  18 , and more precisely to the bevel set crown wheel  45 , and to a drive wheel  2 . 
     The intermediate shaft  24  allow to obtain a first gear module. The electric motor EM 1  is linked to the first gear module. The output shaft  22  allow to obtain a second gear module. The first gear module and the second gear module are arranged to obtain the gearbox  16 . 
     The first intermediate gear  32  can be fixed in rotation with respect to the intermediate shaft  24 , the second intermediate gear  34  and a third intermediate gear  36 . The first intermediate gear  32 , the second intermediate gear  34  and the third intermediate gear  36  can have each a different outer diameter and/or a different number of teeth. Typically, the first intermediate gear  32  can have a diameter that is greater than that of the second intermediate gear  34 , and the second intermediate gear  34  can have a diameter that is greater than that of the third intermediate gear  36 . 
     In the example, the first intermediate gear  32  is integral with the intermediate shaft  24  (i.e. made in one-piece). However, the first intermediate gear  32  could be fixedly attached to the intermediate shaft  24  as well, using fasteners, welding, splines or press-fitting or any other means. Besides, the second intermediate gear  34  and the third intermediate gear  36  are, in this particular arrangement, by default each free to rotate around the intermediate shaft  24 . 
     The axle  10  can have a transmission housing (not shown). The transmission housing can include a central part receiving the differential assembly  18 , and more precisely the bevel set crown wheel  45 , and two lateral parts extending on either side of the central part. The two lateral parts can receive the two drive shafts  40  respectively connected to the drive wheels  2 . The electric motor EM 1  can be arranged so as to transmit a driving torque (or motor torque) to the drive shafts  40  via the differential assembly  18 , and more precisely via the bevel set crown wheel  45 . 
     In this embodiment, the electric motor EM 1 , the differential assembly  18 , the gearbox  16  and the drive wheels  2  are arranged to form the transmission unit. The gearbox  16  includes a multiple speed ratio. 
     Typically, the electric motor EM 1  can be attached to the transmission housing by any appropriate means and in particular by bolting. Such fastening means are known as such, that is why they are not shown on the figures. Alternatively, the housing of the electric motor EM 1  is integral with the transmission housing. 
     The electric motor EM 1  can be offset from a longitudinal direction of the vehicle  1 . 
     The axis of rotation of electric motor EM 1  can be parallel to the longitudinal direction of the vehicle  1 . Accordingly, the transmission unit  14  is said to be in a longitudinal configuration relative to the vehicle  1 . 
     The gearbox  16  can also include a first coupling member  42  (also known as “gear shifting mechanism” or “dog clutch element”), which can be arranged along the output shaft  22 . The first coupling member  42  can be moved between an engaged position, in which it couples the first output gear  26  in rotation with the output shaft  22 , and a neutral position, in which it allows the first output gear  26  to rotate freely around the output shaft  22 . 
     The gearbox  16  can also include a second coupling member  44 , which can be arranged along the intermediate shaft  24 . The second coupling member  44  can be movable between a first position in which it couples the second intermediate gear  34  in rotation with the intermediate shaft  24 , a second position in which it couples the third intermediate gear  36  in rotation with the intermediate shaft  24 , and a neutral position in which it does not prevent the second and third intermediate gears  34 ,  36  from rotating around the intermediate shaft  24 . 
     In one alternative embodiment, the second coupling member  44  could be arranged along the output shaft  22 . In this case, the second coupling member  44  would be movable between a first position in which it would couple the second output gear  28  in rotation with the output shaft  22 , a second position in which it would couple the third output gear  30  in rotation with the output shaft  22 , and a neutral position in which it would not prevent the second and third output gears  28 ,  30  from rotating around the output shaft  22 . 
     At least one of the first coupling member  42  and the second coupling member  44  (preferably both coupling members) can be a dog clutch. 
     In an embodiment, the transmission unit  14  can comprise two electric motors EM 1  and EM 2  (see  FIGS.  8  to  11   ). The two motors EM 1  and EM 2  can be identical in that they have the same characteristics (supply voltage, operating current, torque-speed characteristic, mechanical power, etc.). For example, the mechanical power of EM 1  and EM 2  can be between 50 kW to 500 kw. Alternatively, the two electric motors EM 1  and EM 2  can be different. 
     According to this embodiment, the transmission unit  14  can comprise two primary shafts  20  and two intermediate shafts  24 , as described above, for connecting each electric motor EM 1 , EM 2  to the output shaft  22 . 
     The electric motors EM 1  and/or EM 2  can be AC type motors (synchronous or asynchronous). Alternatively, the electric motors EM 1  and/or EM 2  can be DC type motors as well (brushed). More generally, any electric motor is suitable. 
     The retarder  12  can be connected to the output shaft  22 , as shown in  FIGS.  2  to  6 ,  8  and  11   . 
     In alternative, the retarder  12  can be connected to the intermediate shaft  24 , as shown in  FIGS.  7 ,  9 ,  10   . 
     The retarder  12  can be mounted at the distal end E 12  of the output shaft  22  or at the distal end E 2  of the intermediate shaft  24  relative to the differential assembly  18  ( FIGS.  2 ,  8 ,  11 ,  12 ,  13   ). 
     The retarder  12  can be mounted at the proximal end E 1  of the intermediate shaft  24  relative to the differential assembly  18  ( FIGS.  7 ,  9 ,  10   ). 
     The retarder  12  can be mounted transversely to the electric motor EM 1  with respect to the transversal direction Y of the vehicle  1  ( FIGS.  3 ,  4 ,  7   ). 
     The retarder  12  can be mounted on top of the gearbox  16  ( FIGS.  5 ,  6   ). 
     The retarder  12  can be mounted longitudinally beside the electric motor EM 1 , EM 2 , opposite to the gearbox  16 , with respect to the longitudinal direction X of the vehicle  1  ( FIGS.  9 ,  10   ). 
     In an embodiment, the retarder  12  can be connected to the second extremity E 12  of the output shaft  22 , as illustrated in  FIGS.  2 ,  8  and  11   . For example, a gear arranged on the second extremity E 12  of the output shaft  22  meshes with a gear of the retarder  12 . 
     In another embodiment, the retarder  12  can be connected to the second output gear  28  of the output shaft  22  ( FIGS.  3 ,  5   ). For example, the second output gear  28  meshes with a gear of the retarder  12 . 
     In another embodiment, the retarder  12  can be connected to the third output gear  30  of the output shaft  22  ( FIG.  4 ,  6   ). For example, the third output gear  30  meshes with a gear of the retarder  12 . 
     In another embodiment, the retarder  12  can be connected to the intermediate shaft  24 , as shown in  FIGS.  7 ,  9  and  10   . More precisely, the retarder  12  can be connected to the first extremity E 1  of the intermediate shaft  24 . For example, a gear arranged on the first extremity E 1  of the intermediate shaft  24  meshes with a gear of the retarder  12 . In alternative, the retarder  12  can be connected to the second extremity E 2  of the intermediate shaft  24 . For example, a gear arranged on the second extremity E 2  of the intermediate shaft  24  meshes with a gear of the retarder  12 . 
     In an embodiment illustrated in  FIGS.  11 ,  12  and  13   , the retarder  12  can be connected to the output shaft  22  or to the intermediate shaft  24  via a transmission shaft  23 . Therefore the retarder  12  can be mounted on a chassis of the vehicle  1  or on a non driven axle. 
     As illustrated in  FIGS.  14  to  16  and  18   , the axle  10  can be a non driven axle. Therefore, the retarder  12  can be wheel driven. 
     The axle  10  can comprise a differential assembly  18 ′ and two shafts  40 ′, each shaft  40 ′ being connected to the differential assembly  18 ′ and to a wheel  2  ( FIGS.  15 ,  16   ). The retarder  12  can be connected to the differential assembly  18 ′. The differential assembly  18 ′ can comprise a bevel set crown wheel  45 ′. Each shaft  40 ′ can be connected to the bevel set crown wheel  45 ′. The retarder  12  can be connected to the bevel set crown wheel  45 ′. 
     The axle  10  can be a rear or a front axle. 
     The retarder  12  can be located downstream or upstream of the axle  10  relative to the longitudinal direction of the vehicle  1 . 
     As illustrated in  FIGS.  17  and  18   , the axle  10  can comprise two retarders  12 . The axle  10  comprising two retarders  12  can be a driven or a non driven axle. 
     It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.