Patent Publication Number: US-2019186618-A1

Title: Automated mechanical transmission and system for medium-duty commercial electric vehicles

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/US2017/048897 filed Aug. 28, 2017, which claims priority to U.S. Provisional Application No. 62/379,804 filed on Aug. 26, 2016. The disclosure of the above application is incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates generally to an automated mechanical transmission (AMT) system for medium-duty commercial electric and hybrid vehicles. 
     BACKGROUND 
     Automated mechanical transmission (AMT) systems for vehicle use are known in art. As is well known, an AMT includes a clutch and a collection of gears. The AMT performs gear shifts automatically. AMTs can be provided on many vehicles including line haul vehicles and large construction vehicles. Fuel economy regulations are driving the need for greater fuel efficiency in both line haul and vocational vehicles. Commercial electric vehicles (CEV) and hybrid vehicles eliminate or reduce fuel consumption and can be preferred in some applications. 
     Commercial vehicle transmissions typically have too many gear ratios suitable for application with CEV&#39;s. Electric traction motors for CEV&#39;s generally have very different power and torque characteristics as a function of motor speed. This demands a different configuration of transmission having fewer gears, with gear ratios that are numerically farther apart from each other. Furthermore, light-duty and medium-duty CEV&#39;s often do not have compressed air on board. In this regard, transmission design cannot rely on compressed air to supply actuation input for the transmission. It would be desirable to provide an AMT system suitable for use with an electric motor and that can easily adapt for a wide range of application and gearing requirements. 
     The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. 
     SUMMARY 
     A modular transmission system selectively coupled to an electric motor arranged on a vehicle according to a first example of the present disclosure includes a common front housing, a first rear housing and a second, or alternate, rear housing. The front housing has a transmission motor mount and at least one transmission chassis mount. The transmission motor mount is configured to mount the front housing relative to the electric motor. The at least one transmission chassis mount is configured to mount the front housing relative to a chassis of the vehicle. The first rear housing has a first gear set, or first set of gear ratios. The first rear housing is configured to selectively couple to the front housing to accommodate the first set of gear ratios in the first modular transmission configuration. The second rear housing has a second gear set. The second rear housing is configured to selectively couple to the front housing to accommodate the second set of gear ratios in the second, or alternate, modular transmission configuration. The front housing is configured to selectively and alternatively accept (i) the first rear housing and first gearset for operation in a first modular transmission configuration and (ii) the second rear housing and second gear set for operation in a second modular transmission configuration. 
     According to additional features, the first set is configured as a four speed with no reverse gear and has a Y-Y shifting mechanism—with the “Y-Y” designation meaning both shifters actuate in the same axial direction. In another arrangement, the first gear set is configured as a three speed with no reverse gear and has a Y-Y shifting mechanism. The second gear set is configured as a four speed with reverse gear and has an X-Y shifting mechanism. In another arrangement, the second gear set is configured as a three speed with reverse gear and has a Y-Y shifting mechanism. An adapter plate can mount between the electric motor and the front housing. The front housing can include a transmission mounting plate configured to selectively mate with the electric motor in a first arrangement and the adapter plate in a second arrangement. 
     The first gear set includes a first input gear, a first mainshaft and a first countershaft. The first mainshaft supports a mainshaft first gear, a mainshaft second gear and a mainshaft third gear. The first countershaft supports a countershaft input gear, a countershaft second gear and a countershaft third gear. The second gear set includes a second input gear, a second mainshaft and a second countershaft. The second mainshaft supports a mainshaft first gear, a mainshaft second gear, a mainshaft third gear and a mainshaft reverse gear. The second countershaft defines reverse gear teeth and supports a countershaft input gear, a countershaft second gear and a countershaft third gear. 
     In additional features, the Y-Y shifting mechanism include a motor assembly including a first motor and a second motor configured to provide a shift input for a shift assembly having a first/second sliding clutch and a third/fourth sliding clutch. The shifting mechanism further comprises a first/second shift yoke that actuates the first/second sliding clutch and a third/fourth shift yoke that actuates the third/fourth shift yoke. The modular transmission system is configured as a wet sump. A cover plate can be removable coupled to the rear housing. The cover plate is configured to be removed to access the first countershaft to provide a rotatable input for a power take-off device. 
     In other features, the front housing includes a front housing flange configured to selectively and alternatively align with (i) a first complementary flange on the first rear housing in the first modular transmission configuration and (ii) a second complementary flange on the second rear housing in the second modular transmission configuration. Fasteners can locate through passages defined through the respective front housing flange and (i) first complementary flange in the first modular transmission configuration and (ii) second complementary flange in the second modular transmission configuration. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1A  is a schematic illustration of a modular transmission system assembly constructed in accordance to one example of the present disclosure and shown having a modular transmission system coupled to an exemplary electric motor, the modular transmission system having a front housing, a first gear set and first rear housing according to a first configuration; 
         FIG. 1B  is a schematic illustration of the modular transmission system of  FIG. 1  and shown having the front housing, a second gear set and a second rear housing according to a second configuration; 
         FIG. 2  is a rear perspective view of the modular transmission system of  FIG. 1A ; 
         FIG. 3  is a front perspective view of the modular transmission system of  FIG. 2 ; 
         FIG. 4  is a partial cross-sectional view taken along lines  4 - 4  of the modular transmission system of  FIG. 2 ; 
         FIG. 5A  is a schematic illustration of the modular transmission system of  FIG. 1  and shown highlighting a first gear torque path; 
         FIG. 5B  is a schematic illustration of the modular transmission system of  FIG. 5A  and shown highlighting a second gear torque path; 
         FIG. 5C  is a schematic illustration of the modular transmission system of  FIG. 5A  and shown highlighting a third gear torque path; 
         FIG. 5D  is a schematic illustration of the modular transmission system of  FIG. 5A  and shown highlighting a fourth gear torque path; 
         FIG. 6  is a rear perspective view of the modular transmission system of  FIG. 1B ; 
         FIG. 7  is a front perspective view of the modular transmission system of  FIG. 6 ; and 
         FIG. 8  is a partial cross-sectional view taken along lines  8 - 8  of the modular transmission system of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION 
     With initial reference to  FIG. 1 , a modular transmission system assembly constructed in accordance to one example of the present disclosure is shown and generally referred to at reference  10 A. The modular transmission system assembly  10 A includes a modular transmission system  12 A that is driven by an electric motor  20 . The modular transmission system assembly  10 A can be used in vehicles incorporating an electric motor such as, but not limited to fully electric vehicle and hybrid electric vehicles. In the example shown, the modular transmission system  12 A has a transmission input shaft  22  that is driven by the electric motor  20  and a transmission output shaft  26  that extends outwardly from the modular transmission system  12 A. The output shaft  26  is ultimately drivingly connected with vehicle drive axles  32 , usually by means of a prop shaft  34 . In some examples, a master clutch may be interposed between the electric motor  20  and the transmission input shaft  22 . An optional adapter plate  38  can be arranged between the electric motor  20  and the modular transmission system  12 A to allow for suitable mounting points between the electric motor  20  and the adapter plate  38  as well as between the modular transmission system  12 A and the adapter plate  38 . 
     As will become appreciated from the following discussion, the modular transmission system  12 A includes a split housing design in which a front housing  40  remains common for a plurality of possible electric vehicle AMT configurations whereas a rear housing  42 A ( FIG. 1A ) and  42 B ( FIG. 1B ), having unique gear sets, can be selected depending upon a particular application such as to accommodate various vocational needs. In this regard, the rear housing  42 A can be used that may accommodate a first gear set  44 A. Similarly, the rear housing  42 B can be used that may accommodate a second gear set  44 B. A modular transmission system assembly  10 B, shown in  FIG. 2  includes a modular transmission system  12 B driven by the electric motor  20 . The remaining components of the modular transmission system assembly  10 B can be similar to those described above with respect to the modular transmission system assembly  10 A. 
     While the following discussion is directed to two particular gear sets, the design is not so limited. Explained further, the modular transmission system  12 A can accommodate a wide range of gear sets to accommodate a particular vehicle application. The front housing  40  together with an application specific rear housing (such as  42 A,  42 B) can accept larger or smaller gears, gear sets without reverse gear and with reverse gear (such as  44 A and  44 B, respectively) with minimal to no design change, effectively changing the overall gear ratios. It is contemplated that the only component which requires redesign for different gear sets is the countershaft (explained below) since the first gear is defined therein. The possible gear ratios can range anywhere between 9:1 to direct drive (Max Torque: 900 Nm) and 4:1 to direct drive (Max Torque: 1330 Nm). 
     With particular reference now to  FIGS. 2-4 , the modular transmission system  12 A will be described in greater detail. The front housing  40  includes transmission chassis mounts  50  and  52 . In the example shown, the transmission chassis mounts  50  and  52  are standard SAE housing nodal mounts for flexible chassis to transmission integration. In some arrangements an elastomeric member (not shown) can be interposed between the chassis mounts  50 ,  52  and the frame rails of the chassis. The front housing  40  can include a front housing flange  60  configured to align with a complementary flange  62  provided on the rear housing  42 A. Fasteners  66  can extend through passages defined through the respective flanges  60 ,  62  to couple the front housing  40  to the rear housing  42 A. A cover plate  70  is removably coupled to the rear housing  42 A. As will become appreciated, the cover plate  70  can be removed to access a countershaft for optionally providing a rotatable input for a power take off (PTO) device (such as an actuation mechanism for a refuse truck). 
     A motor assembly  72  includes a first motor  72 A and a second motor  72 B that are arranged in a Y-Y configuration and provide a shift input for a shift assembly  74 . The front housing  40  defines a transmission mounting plate  80  having a plurality of transmission mounting points  82 . In some examples, the transmission mounting points  82  can align with complementary motor mounting points  84  defined on the electric motor  20  for receiving fasteners that couple the front housing  40  and therefore the modular transmission  12 A to the electric motor  20 . In other examples, the adapter plate  38  can have a first set of mounting points  90  and a second set of mounting points  92 . The first set of mounting points  90  align with the transmission mounting points  82  for receiving fasteners that couple the front housing  40  to the adapter plate  38 . The second set of mounting points  92  align with the motor mounting points  82  for receiving fasteners that couple the adapter plate  38  to the electric motor  20 . It will be appreciated that other mounting arrangements may be incorporated for coupling the front housing  40  with the electric motor  20  within the scope of the present disclosure. 
     With reference now to  FIG. 4 , a first gear set  44 A associated with the rear housing  42 A of the modular transmission system  12 A will be described. The first gear set  44 A include a mainshaft  100  and a countershaft  102 . In the example shown, the mainshaft  100  is coaxial with the transmission input shaft  22 . The countershaft  102  is offset from the input shaft  22  and the mainshaft  100 . The output shaft  26  may be coaxial with the mainshaft  100 . The transmission input shaft  22  can be splined for rotation with an input gear  110 . 
     The mainshaft  100  is supported in the modular transmission system  12 A by a front mainshaft bearing  120  and a rear mainshaft bearing  122 . The mainshaft  100  rotatably supports a mainshaft first gear  130 , a mainshaft second gear  132 , and a mainshaft third gear  134 . A first/second sliding clutch  140  is actuated by a first/second shift yoke  142 . A third/fourth sliding clutch  150  is actuated by a third/fourth shift yoke  152 . The countershaft  102  is supported in the modular transmission system  12 A by a front countershaft bearing  156  and a rear countershaft bearing  158 . The countershaft  102  rotatably supports a countershaft input gear  160 , a countershaft second gear  162  and a countershaft third gear  164 . Countershaft first gear teeth  166  are defined on the countershaft  102  for meshingly engaging the mainshaft first gear  130 . A wet sump  170  can be provided in the modular transmission  12 A having adaptable oil level. 
       FIGS. 5A-5D  illustrate the modular transmission system  12 A configured for four speeds. In this regard, various torque paths are achieved for first, second, third and fourth gear speeds based on the positioning of the first/second sliding clutch  140  and the third/fourth sliding clutch  150 .  FIG. 5A  shows the first gear set  44 A in a first gear power path.  FIG. 5B  shows the first gear set  44 A in a second gear power path.  FIG. 5C  shows the first gear set  44 A in a third gear power path.  FIG. 5D  shows the first gear set  44 A in a fourth gear power path, also known in the art as direct-drive with a ratio of 1:1. It is appreciated that the first gear set  44 A can also be configured for operation in less than four speeds. 
     With reference to  FIGS. 6-8 , the rear housing  42 B including the second gear set  44 B will be described. A motor assembly  272  includes a first motor  272 A and a second motor  272 B that are arranged in an X-Y configuration and provide a shift input for a shift assembly  274  ( FIG. 8 ). As identified above, the rear housing  42 B can include a different gear set than the rear housing  42 A to achieve different gear ratios and/or gear combinations. In the exemplary gear set  44 B, a four speed transmission with reverse gear is provided. 
     The first gear set  44 B includes a mainshaft  300  and a countershaft  302 . In the example shown, the mainshaft  300  is coaxial with the transmission input shaft  22 . The countershaft  302  is offset from the input shaft  22  and the mainshaft  300 . The output shaft  26  may be coaxial with the mainshaft  300 . The transmission input shaft  22  can be splined for rotation with an input gear  310 . The mainshaft  300  is supported in the modular transmission  12 B by a front mainshaft bearing  320  and a rear mainshaft bearing  322 . The mainshaft  300  rotatably supports a mainshaft first gear  330 , a mainshaft second gear  332 , a mainshaft third gear  334 , and a mainshaft reverse gear  336 . A first/second sliding clutch  340  is actuated by a first/second shift yoke  342 . A third/fourth sliding clutch  350  is actuated by a third/fourth shift yoke  352 . The countershaft  302  is supported in the modular transmission  12 B by a front countershaft bearing  356  and a rear countershaft bearing  358 . The countershaft  302  rotatably supports a countershaft input gear  360 , a countershaft second gear  362  and a countershaft third gear  364 . Countershaft first gear teeth  366  are defined on the countershaft  302  for meshingly engaging the mainshaft first gear  330 . Countershaft second (reverse) gear teeth  368  are defined on the countershaft  302  for meshingly engaging the mainshaft reverse gear  336 . A wet sump  370  can be provided in the modular transmission  12 B having adaptable oil level. 
     The transmission system assembly  10  of the present disclosure provides a solution for an extremely broad and under-defined CEV market. The transmission system assembly  10  is adaptable to a wide range of electric motors, vehicle chassis and vocations that require distinct gear ratios all while maintaining a simple low cost design which can be easily integrated into the powertrain system for a wide range of original equipment manufacturers. The housings  40 ,  42 A,  42 B accept larger or smaller gears with minimal to no design change, effectively changing the overall gear ratios. In some instances, the countershaft  102 ,  302  would require redesign to account for any gears cut thereon. 
     The foregoing description of the examples has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular example are generally not limited to that particular example, but, where applicable, are interchangeable and can be used in a selected example, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.