Patent Publication Number: US-2021188076-A1

Title: Electromechanical variable transmission

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 16/592,167, filed Oct. 3, 2019, which is a continuation of U.S. application Ser. No. 16/042,680, filed Jul. 23, 2018, which is a continuation of U.S. application Ser. No. 15/247,907, filed Aug. 25, 2016, now U.S. Pat. No. 10,029,556, which is a continuation of U.S. application Ser. No. 14/514,210, filed Oct. 14, 2014, now U.S. Pat. No. 9,428,042, which is a continuation of U.S. application Ser. No. 13/686,678, filed Nov. 27, 2012, now U.S. Pat. No. 8,864,613, which is a continuation of U.S. application Ser. No. 12/820,928, filed Jun. 22, 2010, now U.S. Pat. No. 8,337,352, all of which are incorporated herein by reference in their entireties. 
    
    
     STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH OR DEVELOPMENT 
     The government of the United States has certain rights in this invention pursuant to Contract No. N00014-09-C-0601 awarded by the Office of Naval Research. 
    
    
     BACKGROUND 
     The present disclosure relates generally to the field of transmissions for vehicles. More specifically, the present disclosure relates to the field of electromechanical infinitely variable transmissions for vehicles. 
     SUMMARY 
     One exemplary embodiment relates to a drive train for a vehicle, the drive train including a first gear set including a sun gear, a ring gear and planetary gears coupling the sun gear to the ring gear, a second gear set including a sun gear, a ring gear and planetary gears coupling the sun gear to the ring gear, a first motor/generator coupled to the first gear set, a second motor/generator coupled to the second gear set, and at least one of (a) a first clutch that selectively engages the second motor/generator with the first gear set and (b) a second clutch that selectively engages the ring gear of the second gear set with the planetary gear carrier of at least one of the first gear set and the second gear set. The planetary gears of both sets are rotatably supported by respective planetary gear carriers. 
     Another exemplary embodiment relates to a drive train for a vehicle, the drive train including a first planetary gear set, a second planetary gear set directly attached to the first planetary gear set, an output shaft coupled to at least one of the first and the second planetary gear sets and radially offset from the first and second planetary gear sets, a first electromagnetic device directly coupled to the first planetary gear set, and a second electromagnetic device coupled to the second planetary gear set and selectively rotationally engaged with the first planetary gear set. 
     Another exemplary embodiment relates to a vehicle including a transmission including a first gear set having a first planetary gear carrier and a second gear set having a second planetary gear carrier, a first motor/generator coupled to the first gear set, and a second motor/generator coupled to the second gear set. During a first mode of operation of the vehicle the second motor/generator is disengaged from the first gear set. During a second mode of operation of the vehicle the second motor/generator is coupled to the first gear set. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of drive train for a vehicle according to an exemplary embodiment. 
         FIG. 2  is a detailed schematic view of the drive train shown in  FIG. 1  according to an exemplary embodiment. 
         FIG. 3  is a schematic diagram of a control system for the drive train shown in  FIG. 1  according to an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a schematic view of a drive train for a vehicle V 1  is shown according to an exemplary embodiment. The vehicle V 1  may be a work or commercial vehicle, a military vehicle, or any other type of vehicle. 
     According to an exemplary embodiment, the drive train includes an engine E 1  coupled to a transmission T 1 . The vehicle V 1  also includes a first electromagnetic device EM 1  coupled to the transmission T 1  and a second electromagnetic device EM 2  coupled to the transmission T 1 . The vehicle V 1  also includes at least one drive axle (such as, e.g., rear axle RA 1  and/or front axle FA 1 ) coupled to the transmission T 1 . 
     According to an exemplary embodiment, the engine E 1  is configured to provide rotational mechanical energy to the transmission T 1 . The engine E 1  may be any source of rotational mechanical energy which is derived from a stored energy source such as a liquid or gaseous fuel. Examples are an internal combustion engine (such as a gas, natural gas, or diesel powered engine), turbine, fuel cell, electric motor or any other type of motor capable of providing rotational mechanical energy to the transmission T 1 . According to one exemplary embodiment, the engine E 1  is a twelve liter diesel engine capable of providing approximately 400 to 600 horsepower, 400-1500 ft-lbs of torque, and has a rotational speed of approximately 0 to 2100 rpm. According to one exemplary embodiment, the engine E 1  is operated at a relatively constant speed (such as, e.g., 1600 rpm) to maximize fuel efficiency. 
     According to an exemplary embodiment, the electromagnetic devices EM 1 , EM 2  are electric motor/generator devices that are capable of providing rotational electrical energy (as an electric motor) and/or capable of producing electrical power (as a generator). According to one exemplary embodiment, the electromagnetic devices EM 1 , EM 2  provide electric power to one another, depending on the specific mode of operation of the vehicle V 1 . For example, the first electromagnetic device EM 1  may be operated as a generator to provide electric power to the second electromagnetic device EM 2 . Alternatively, the second electromagnetic device EM 2  may be operated as a generator to provide electric power to the first electromagnetic device EM 1 . 
     According to one exemplary embodiment, the first electromagnetic device EM 1  and the second electromagnetic device EM 2  may be the same (or similar) to one another. However, according to other exemplary embodiments, the first electromagnetic device EM 1  and the second electromagnetic device EM 2  may be sized differently as required by a particular application. According to one exemplary embodiment, the electromagnetic devices EM 1 , EM 2  are each capable of providing up to approximately 300 horsepower and 1300 ft-lbs of torque and are capable of rotational speeds from approximately −6,000 to 6,000 rpm (i.e., both forward and reverse from 0 to 6,000 rpm). 
     According to an exemplary embodiment, the transmission T 1  is coupled to at least one drive axle of the vehicle V 1  (such as, e.g., rear axle RA 1  and/or front axle FA 1  as shown in  FIG. 1 ). According to one exemplary embodiment, both the rear axle RA 1  and the front axle FA 1  are driven by the transmission T 1 . According to other exemplary embodiments, only one of the axles may be driven by the transmission T 1 . According to yet another exemplary embodiment, additional axles (e.g., such as additional rear axles not shown) may be driven by the transmission T 1 . According to an exemplary embodiment, each of the axles are coupled to the transmission via a differential gear set (such as, e.g., rear differential RD 1  and/or front differential FD 1  shown in  FIG. 1 ). Each axle is configured to drive (i.e., provide rotational energy to) one or more wheels/tires to propel (e.g., move, push, drive etc.) the vehicle V 1 . 
     Referring now to  FIG. 2 , a detailed schematic view of the drive train for the vehicle V 1  is shown according to exemplary embodiment. As shown in  FIG. 2 , the transmission T 1  includes two planetary gear sets. According to an exemplary embodiment, the transmission T 1  includes a first planetary gear set P 1  and a second planetary gear set P 2 . A third planetary gear set P 3  is provided as a torque divider (e.g., 30% torque to the front and 70% torque to the rear) if both the front and rear vehicle axles are powered. 
     According to one exemplary embodiment, the first planetary gear set P 1  is configured as a power split device or power splitting planetary gear set, the second planetary gear set P 2  is configured as a gear reduction device, and the third planetary gear set P 3  is configured as a torque proportioning device. As shown in  FIG. 2 , the first planetary gear set P 1  is coupled to the engine E 1 , the first electromechanical device EM 1 , the second electromechanical device EM 2  (via the second planetary gear set P 2 ), and to gear G 5 . The second planetary gear set P 2  is also coupled to the gear G 5  (via gears G 13 , G 14 , G 15 , clutch C 2  and shaft S 6 ). 
     As shown in  FIG. 2 , the engine E 1  is coupled to a clutch C 3  that is configured to selectively rotationally engage/disengage the engine E 1  with the transmission T 1 . The clutch C 3  may be any type of clutch capable of rotationally fixing the engine E 1  to the transmission T 1 . When the clutch C 3  is engaged, the engine E 1  is coupled to a shaft S 1 . A gear G 6  is coupled (e.g., rotationally fixed) to shaft S 1  and engages a gear G 7  that is coupled (e.g., rotationally fixed) to a shaft S 2 . The gear G 7  in turn is coupled to the first planetary gear set P 1  via the shaft S 2 . 
     As shown in  FIG. 2 , the first planetary gear set P 1  comprises an annulus or ring gear G 1  which is coupled to the shaft S 2 . As shown, the clutch C 3 , the gears G 6  and G 7 , and the shaft S 2  cooperate to permit engine E 1  to drive the ring gear G 1 . The ring gear G 1  is engaged with at least one planetary gear G 2  (e.g., one, two, three, four or more planetary gears G 2  that are coupled to one another (e.g., rotatably supported) by a planetary gear carrier PGC 1 ). The planetary gear(s) G 2  are engaged with a sun gear G 3  of the first planetary gear set P 1  to couple the ring gear G 1  to the sun gear G 3 . 
     The sun gear G 3  is directly coupled to the first electromagnetic device EM 1  by a shaft S 3 . The first electromagnetic device EM 1  may be coupled to an optional brake B 1  by a clutch C 4 . The clutch C 4  may be any type of clutch capable of rotationally fixing the first electromagnetic device EM 1  to the brake B 1 . The effect of braking the first electromechanical device EM 1  is to fix or hold sun gear G 3  without the need to apply electrical energy to the first electromechanical device EM 1  to cause the first electromechanical device EM 1  to generate enough holding torque to hold the gear G 3  from rotating. 
     According to an exemplary embodiment, the planetary gear carrier PGC 1  is coupled to a carrier gear G 4 . The carrier gear G 4  is engaged with a gear G 5 . In the preferred embodiment of vehicle V 1 , the gear G 5  is part of the third planetary gear set P 3  used to divide the power from the transmission T 1  to the front and rear axles. In this embodiment, the gear G 5  is coupled to the planetary gears of the third planetary gear set P 3 . If only a single axle is driven by the transmission T 1 , or a different transfer device is used to drive more than one axle, the third planetary gear set P 3  may not be necessary. 
     The carrier gear G 4  is also coupled to the second planetary gear set P 2  by a shaft S 5  (as will be described in more detail below). 
     Still referring to  FIG. 2 , the transmission T 1  also includes a clutch C 1  that selectively rotationally engages/disengages the engine E 1  to the second electromagnetic device EM 2 . The clutch C 1  may be any type of clutch capable of rotationally fixing the engine E 1  to the second electromagnetic device EM 2 , such as a wet clutch. 
     As shown in  FIG. 2 , the clutch C 1  is coupled to the engine E 1  by the shaft S 1 . When the clutch C 1  is engaged, the shaft S 1  is coupled to a gear G 9 . The gear G 9  in turn is engaged with a gear G 8  that is coupled to the second electromagnetic device EM 2 . Thus, when the clutch C 1  is engaged, the engine is coupled to the second electromagnetic device EM 2  to allow the second electromagnetic device EM 2  to be driven as a generator (e.g., to provide electrical power to the first electromagnetic device EM 1 ). 
     The electromagnetic device EM 2  is also coupled to the second planetary gear set P 2  by a shaft S 4 . The shaft S 4  is connected to a sun gear G 12  of the second planetary gear set P 2 . The sun gear G 12  is engaged with at least one planetary gear G 11  (e.g., one, two, three, four or more planetary gears G 11  that are coupled to one another (e.g., rotatably supported) by a planetary gear carrier PGC 2 ). The planetary gear(s) G 11  in turn are engaged with an annulus or ring gear G 10  to couple the sun gear G 12  to the ring gear G 10 . 
     According to an exemplary embodiment, the planet gear carrier PGC 2  of the second planetary gear P 2  is coupled to the carrier gear G 4  (and the planet gear carrier PGC 1 ) of the first planetary gear set P 1  by a shaft S 5 . Thus, the planet gear carrier PGC 1  and the planet gear carrier PGC 2  are coupled to one another so that the second electromagnetic device EM 2  is coupled to the first planetary gear set Pb via the second planetary gear set P 2 . 
     The second electromagnetic device EM 2  is also coupled to the third planetary gear set P 3  via the second planetary gear set P 2 . According to an exemplary embodiment, the ring gear G 10  of the second planetary gear P 2  is coupled to an output gear G 13  that is engaged with an idler gear G 14 . The idler gear G 14  in turn is engaged with a gear G 15  that is selectively engaged/disengaged to the third planetary gear set P 3  by a clutch C 2  (via a shaft S 6 ). The clutch C 2  may be any type of clutch capable of rotationally fixing the gear G 15  to the shaft S 6 , such as a wet clutch. 
     According to an exemplary embodiment, the third planetary gear set P 3  is a torque proportioning device for the front and rear axles of the vehicle V 1 . Torque is delivered from the third planetary gear set P 3  to the front axle FA 1  and/or the rear axle RA 1  via shafts S 7  and S 8 . As discussed above, in other exemplary embodiments, the third planetary gear set P 3  is not necessary when either the front axle FA 1  or rear axle RA 1  of the vehicle V 1  is not driven by the transmission T 1 . 
     According to an exemplary embodiment, the transmission T 1  is operated in a low speed mode (e.g., a vehicle speed of approximately 0-10 mph) by having the clutch C 2  engaged and the clutch C 1  disengaged. According to another exemplary embodiment, the transmission T 1  is operated in a high speed mode (e.g., a vehicle speed of approximately 10-65 mph) by having the clutch C 1  engaged and the clutch C 2  disengaged. According to other various embodiments, the vehicle speeds in the low and high speed modes may vary higher or lower. 
     According to an exemplary embodiment, an operator (e.g., driver) of vehicle V 1  may manually switch the transmission T 1  from low speed mode to high speed mode or vice-versa. According to another exemplary embodiment, the transmission T 1  is automatically switched from low speed mode to high speed mode (and vice-versa) by a control system (see, e.g.,  FIG. 3 ). The control system may include various operator inputs (such as, e.g., desired vehicle speed, torque, traction, terrain, etc.) and also various system inputs (such as, e.g., current vehicle speed, engine speed, power, and torque, electromagnetic device speed, power, and torque, etc.). As shown in  FIG. 3 , according to one exemplary embodiment, the control system is configured to monitor and/or control the engine, the mode of the transmission, the first electromagnetic device EM 1 , the second electromagnetic device EM 2 , the clutch C 1 , the clutch C 2 , and/or the clutch C 3 . 
     According to an exemplary embodiment, gears within the transmission T 1  are sized according to the specific application and desired performance characteristics of the vehicle V 1 . According to one exemplary embodiment, the gears within the transmission T 1  have tooth counts as shown in Table  1 . However, according to other exemplary embodiments, the tooth counts of the gears may vary more or less than that shown. According to other exemplary embodiments, the engine E 1 , the electromagnetic devices EM 1  and EM 2 , the clutches C 1 -C 4 , and the shafts S 1 -S 8  may all vary according to the specific application and desired performance characteristics of the vehicle V 1 . 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                 Tooth 
               
               
                   
                 Gear # 
                 Count 
               
               
                   
                   
               
             
            
               
                   
                 Gear 1 
                 81 
               
               
                   
                 Gear 2 
                 24 
               
               
                   
                 Gear 3 
                 33 
               
               
                   
                 Gear 4 
                 77 
               
               
                   
                 Gear 5 
                 77 
               
               
                   
                 Gear 6 
                 49 
               
               
                   
                 Gear 7 
                 50 
               
               
                   
                 Gear 8 
                 55 
               
               
                   
                 Gear 9 
                 74 
               
               
                   
                 Gear 10 
                 64 
               
               
                   
                 Gear 11 
                 19 
               
               
                   
                 Gear 12 
                 26 
               
               
                   
                 Gear 13 
                 28 
               
               
                   
                 Gear 14 
                 47 
               
               
                   
                 Gear 15 
                 82 
               
               
                   
                   
               
            
           
         
       
     
     It should be noted that references to “front,” “rear,” “top,” and “base” in this description are merely used to identify various elements as are oriented in the FIGS., with “front” and “rear” being relative to the environment in which the device is provided. 
     For the purpose of this disclosure, the term “coupled” means the joining of two members directly or indirectly to one another. Such joining may be stationary or moveable in nature. Such joining may be achieved with the two members or the two members and any additional intermediate members being integrally formed as a single unitary body with one another or with the two members or the two members and any additional intermediate members being attached to one another. Such joining may be permanent in nature or may be removable or releasable in nature. 
     It is important to note that the construction and arrangement of the electromechanical variable transmission as shown in the various exemplary embodiments is illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (for example, variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the claims. For example, elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes and omissions may also be made in the design, operating conditions and arrangement of the various exemplary embodiments without departing from the scope of the present embodiments.