Patent Publication Number: US-11396286-B2

Title: Hybrid-vehicle system

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention generally relates to a hybrid-vehicle system and a method for controlling an assembly for a hybrid-vehicle system. 
     2. Description of the Related Art 
     Hybrid-vehicle systems for vehicles include an internal combustion engine and an electric motor. In these hybrid-vehicle systems, both the internal combustion engine and the electric motor are capable of delivering torque to wheels of the vehicle to propel the vehicle. Commonly, the internal combustion engine and the electric motor are capable of delivering the torque to a transmission, which, in turn, delivers the torque to the wheels of the vehicle. Hybrid-vehicle systems also commonly include an assembly to selectively transmit the torque from the internal combustion engine and/or the electric motor to the transmission. 
     The assemblies common to hybrid-vehicle systems typically include a clutch moveable between engaged and disengaged states to selectively transmit the torque from the internal combustion engine and/or the electric motor to the transmission. The clutch must be continuously held in the engaged state to transmit the torque from the internal combustion engine and/or the electric motor through the friction clutch to the transmission, thus requiring continuous use of electric and/or hydraulic power to continuously hold the friction clutch in the engaged state. The continuous use of electric and/or hydraulic power increases the energy consumption of the assembly, increases the cost to operate the assembly, and increases the possibility of failure of the assembly. 
     As such, there remains a need to provide an improved assembly for a hybrid-vehicle system. 
     SUMMARY OF THE INVENTION AND ADVANTAGES 
     A hybrid-vehicle system for a vehicle is disclosed. The hybrid-vehicle system includes an internal combustion engine including a crankshaft. The internal combustion engine is configured to deliver a first rotational torque to the crankshaft. The hybrid-vehicle system also includes a transmission selectively rotatably coupled to the crankshaft of the internal combustion engine. The hybrid-vehicle system further includes an assembly. 
     The assembly includes an electric machine rotatably coupled to the transmission, and the electric machine is configured to deliver a second rotational torque directly to the transmission in conjunction with the first rotational torque from the internal combustion engine or independent of the first rotational torque from the internal combustion engine. The assembly also includes a one-way clutch coupled to the crankshaft, and the one-way clutch is configured to rotationally couple the crankshaft and the transmission to selectively deliver rotational torque from the crankshaft through the one-way clutch to the transmission. The assembly further includes a friction clutch coupled to the crankshaft, and the friction clutch is moveable between an engaged state and a disengaged state. 
     When the friction clutch is in the engaged state, the crankshaft and the transmission are rotationally coupled to selectively deliver a portion of the first rotational torque from the crankshaft through the friction clutch to the transmission. When the friction clutch is in the disengaged state, the crankshaft and the transmission are rotationally decoupled and the first rotational torque from the crankshaft is not transmitted through the friction clutch. The friction clutch is further defined as a latching friction clutch. 
     The movement of the friction clutch between the engaged and disengaged states to rotationally couple and selectively deliver the portion of the first rotational torque from the crankshaft through the friction clutch to the transmission is optimally accomplished due to the ability of the friction clutch to smoothly engage and disengage. Thus, the friction clutch prevents damage to the assembly, the internal combustion engine, and/or the electric machine during engagement of the friction clutch. The friction clutch also produces a smooth driving experience of the vehicle. 
     The latching friction clutch is able to remain in the engaged state without additional power consumption, such as hydraulic power consumption or electrical power consumption. As such, the latching friction clutch results in low power consumption during steady-state operation of the internal combustion engine without sacrificing delivery of the torque to the transmission. Additionally, the latching friction clutch may allow the one-way clutch to be configured to deliver less than 100% of the first rotational torque to the transmission because the latching friction clutch may deliver the portion of the first rotational torque from the crankshaft through the latching friction clutch to the transmission without adversely affecting power consumption of the hybrid-vehicle system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
         FIG. 1A  is a schematic illustration of a hybrid-vehicle system having an internal combustion engine, an electric machine, a transmission, a latching friction clutch in a disengaged state, and a one-way clutch; 
         FIG. 1B  is a schematic illustration of the hybrid-vehicle system, with the latching friction clutch in an engaged state; 
         FIG. 2A  is a schematic illustration of the hybrid-vehicle system, with the latching friction clutch in the disengaged state, and with the one-way clutch having a one-way clutch output that is rotationally coupled to the transmission without being rotationally coupled to the electric machine; and 
         FIG. 2B  is a schematic illustration of the hybrid-vehicle system, with the latching friction clutch in the engaged state. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to the Figures, wherein like numerals indicate like parts throughout the several views, a hybrid-vehicle system  10  for a vehicle is shown schematically in  FIGS. 1A-2B . The hybrid-vehicle system  10  includes an internal combustion engine  12  including a crankshaft  14 . The internal combustion engine  12  is configured to deliver a first rotational torque to the crankshaft  14 . The first rotational torque may be a maximum torque deliverable by the internal combustion engine  12 . 
     The internal combustion engine  12  has a cylinder and a piston disposed in the cylinder. During operation of the internal combustion engine  12 , the piston is moved by combustion in the cylinder, which then rotates the crankshaft  14  and delivers a torque to the crankshaft  14 . The hybrid-vehicle system  10  also includes a transmission  16  selectively rotatably coupled to the crankshaft  14  of the internal combustion engine  12 . The hybrid-vehicle system  10  further includes an assembly  18 . 
     The assembly  18  includes an electric machine  20  rotatably coupled to the transmission  16 , and the electric machine  20  is configured to deliver a second rotational torque directly to the transmission  16  in conjunction with the first rotational torque from the internal combustion engine  12  or independent of the first rotational torque from the internal combustion engine  12 . Although not required, the electric machine  20  may be an electric motor configured to convert electrical energy into rotational energy and torque, and/or may be an electric generator configured to convert rotational energy and torque into electrical energy. The assembly  18  also includes a one-way clutch  22  coupled to the crankshaft  14 . The one-way clutch  22  is configured to rotationally couple the crankshaft  14  and the transmission  16  to selectively deliver rotational torque from the crankshaft  14  through the one-way clutch  22  to the transmission  16 . The assembly  18  further includes a friction clutch  24  coupled to the crankshaft  14 . The friction clutch  24  is moveable between an engaged state and a disengaged state. 
     When the friction clutch  24  is in the engaged state, as shown in  FIGS. 1A and 2A , the crankshaft  14  and the transmission  16  are rotationally coupled to selectively deliver a portion of the first rotational torque from the crankshaft  14  through the friction clutch  24  to the transmission  16 . When the friction clutch  24  is in the disengaged state, as shown in  FIGS. 1B and 2B , the crankshaft  14  and the transmission  16  are rotationally decoupled and the first rotational torque from the crankshaft  14  is not transmitted through the friction clutch  24 . The friction clutch  24  is further defined as a latching friction clutch  26 . 
     The movement of the latching friction clutch  26  between the engaged and disengaged states to rotationally couple and selectively deliver a portion of the first rotational torque from the crankshaft  14  through the latching friction clutch  26  to the transmission  16  is optimally accomplished due to the ability of the latching friction clutch  26  to smoothly engage and disengage. The friction clutch  24  is able to smoothly engage and disengage because the friction clutch  24  has at least one friction plate able to partially engage while moving between the disengaged and engaged states. Partial engagement of the friction plate prevents abrupt transmission of the torque from the crankshaft  14  to the transmission  16 . Thus, the latching friction clutch  26  prevents damage to the assembly  18 , the internal combustion engine  12 , and/or the electric machine  20  during engagement of the latching friction clutch  26 . The latching friction clutch  26  also produces a smooth driving experience of the vehicle. 
     The latching friction clutch  26  is able to remain in the engaged state without additional power consumption, such as hydraulic power consumption or electrical power consumption. As such, the latching friction clutch  26  results in low power consumption during steady-state operation of the internal combustion engine  12  without sacrificing delivery of the torque to the transmission  16 . Additionally, the latching friction clutch  26  may allow the one-way clutch  22  to be configured to deliver less than 100% of the first rotational torque to the transmission  16  because the latching friction clutch  26  may deliver the portion of the first rotational torque from the crankshaft  14  through the latching friction clutch  26  to the transmission  16  without adversely affecting power consumption of the hybrid-vehicle system  10 . 
     Typically, the latching friction clutch  26  has a latch  38  configured to prevent the latching friction clutch  26  from moving from the engaged state to the disengaged state. The latch  38  may be mechanical, such as a ball-and-spring detent, a pawl or ratchet, a plug disposed in a fluid flow path defined in the latching friction clutch  26 , a separator plate disposed between friction plates and configured to engage a housing or another plate to remain in the engaged state, or a hydraulic or electric piston coupled to the separator plate and/or the friction plates and configured to engage the housing or another plate to remain in the engaged state. Although not required, when the latch  38  is a ball-and-spring detent, the ball in the engaged state is disposed in one or more of a groove, recess, depression, indentation, or the like of the housing, the hydraulic or electric piston, the separator plate, or another plate. 
     The latching friction clutch  26  and the one-way clutch  22  are disposed in parallel with one another. Said differently, the torque from the crankshaft  14  may be delivered through the latching friction clutch  26  to the transmission  16 , the torque from the crankshaft  14  may be delivered through the one-way clutch  22  to the transmission  16 , or the torque from the crankshaft  14  may be delivered through both the latching friction clutch  26  and the one-way clutch  22  to the transmission  16 . 
     During start-up of the internal combustion engine  12 , the crankshaft  14  begins rotating at a rotational speed. During start-up of the internal combustion engine  12 , the electric machine  20  may be required to supplement the torque delivered by the crankshaft  14  of the internal combustion engine  12 . For the electric machine  20  to supplement the torque delivered by the crankshaft  14  of the internal combustion engine  12 , the electric machine must be synchronized with the rotational speed of the crankshaft  14 . To synchronize the rotational speed of the crankshaft  14  and the electric machine  20 , the latching friction clutch  26  may be moved from the disengaged state to the engaged state to smoothly rotational couple the crankshaft  14  and the electric machine  20 . The latching friction clutch  26  is able to synchronize the rotation of the crankshaft  14  and the electric machine  20  without aid from any external devices. 
     After the latching friction clutch  26  is in the engaged state and the rotation of the crankshaft  14  and the electric machine  20  are synchronized, the one-way clutch  22  may be moved from the disengaged state to the engaged state to provide additional capacity to deliver the torque from the internal combustion engine  12  to the transmission  16 . Because the rotational speed of the crankshaft  14  and the electric machine  20  are already synchronized and the crankshaft  14  and the electric machine  20  are already rotationally coupled, the engagement of the one-way clutch  22  can be accomplished without rough transmission of the torque to the transmission  16 , avoiding potential damage to the assembly  18 , the internal combustion engine  12 , and/or the electric machine  20 . 
     It is to be appreciated that the crankshaft  14  and the electric machine  20  are not required to be at the same rotational speed relative to one another to move the one-way clutch  22  from the disengaged state to the engaged state. As the latching friction clutch  26  is engaged, a differential in rotational speed between the crankshaft  14  and the electric machine  20  is decreased. This decrease in the differential in rotational speed between the crankshaft  14  and the electric machine  20  may also allow the one-way clutch  22  to be moved to the engaged state without rough transmission of the torque to the transmission  16 , and may also avoid potential damage to the assembly  18 , the internal combustion engine  12 , and/or the electric machine  20 . 
     After the one-way clutch  22  is moved from the disengaged state to the engaged state, the latching friction clutch  26  may be moved from the engaged state to the disengaged state to reduce power consumption of the hybrid-vehicle system  10 . More specifically, the hybrid-vehicle system  10  may include a pump to hydraulically actuate the latching friction clutch  26  to hold the latching friction clutch  26  in the engaged state, may include a solenoid to electrically actuate the latching friction clutch  26  to hold the latching friction clutch  26  in the engaged state, or may include an electric motor and, optionally, a gear, a lever, a ramp, or a series of gears, levers, and/or ramps to change the torque ratio of the electric motor and to hold the latching friction clutch  26  in the engaged state. To move the latching friction clutch  26  from the engaged state to the disengaged state, the pump, solenoid, and/or electric motor are turned off, thus reducing power consumption of the hybrid-vehicle system  10 . Alternatively, the latching friction clutch  26  may remain in the engaged state to provide capacity beyond the capacity of the one-way clutch  22  to deliver the torque to the transmission  16 . 
     Beyond propelling the vehicle, the latching friction clutch  26  while in the engaged state may allow negative torque transmission from the internal combustion engine  12 . Negative torque transmission is transmission of torque in an opposite rotational direction as typical during operation of the internal combustion engine  12  (e.g. counterclockwise if normally clockwise, or clockwise if normally counterclockwise). The negative torque transmission may be used to slow the vehicle without the aid of external brakes. Without the latching friction clutch  26  allowing the negative torque transmission, the one-way clutch  22  would overrun. 
     The hybrid-vehicle system  10  may also include a damper  28  coupled to the crankshaft  14  of the internal combustion engine  12  and both the latching friction clutch  26  and the one-way clutch  22  of the assembly  18 . The damper  28  may be, but is not limited to, a harmonic damper, a centrifugal pendulum absorber, or a dual mass flywheel. The hybrid-vehicle system  10  may further include a transmission launch device coupled to the transmission  16  and to both the latching friction clutch  26  and the one-way clutch  22 . The transmission launch device may be, but is not limited to, a torque converter or a launch clutch. 
     In some embodiments, in the engaged state, the latching friction clutch  26  is limited to delivering 85% or less of the first rotational torque to the transmission  16 . In the embodiments where the latching friction clutch  26  is sized such that the latching friction clutch  26  is limited to delivering 85% or less of the first rotational torque to the transmission  16 , the size of the assembly  18  is decreased, the cost of the assembly  18  is lowered, and the heat generation caused by the latching friction clutch  26  in the assembly  18  is limited. 
     Although not required, in one embodiment, the latching friction clutch  26  in the engaged state is limited to delivering 70% or less of the first rotational torque to the transmission  16 . It is to be appreciated that the latching friction clutch  26  may be limited to delivering 50% or less of the first rotational torque to the transmission  16 , may be limited to delivering 40% or less of the first rotational torque to the transmission  16 , may be limited to delivering 30% or less of the first rotational torque to the transmission  16 , and/or may be limited to delivering 20% or less of the first rotational torque to the transmission  16 . 
     The particular percentage of the first rotational torque at which the latching friction clutch  26  is limited to delivering may be determined by, but is not limited to, the torque from the internal combustion engine  12  between start-up of the internal combustion engine  12  and the torque at which the rotational speed of the crankshaft  14  and the electric machine  20  are synchronized. This torque is typically less than the first rotational torque, which is the maximum torque deliverable by the internal combustion engine  12 . 
     In some embodiments, the one-way clutch  22  is configured to deliver at least 100% of the first rotational torque from the crankshaft  14  to the transmission  16 . In the embodiments where the one-way clutch  22  is configured to deliver at least 100% of the first rotational torque from the crankshaft  14  to the transmission  16 , the one-way clutch  22  is able to be in an engaged state during steady-state operation of the internal combustion engine  12  while the latching friction clutch  26  is in the disengaged state while not limiting the amount of the first rotational torque able to be delivered to the transmission  16 . In other words, in these embodiments, the one-way clutch  22  is able to deliver all of the first rotational torque from the internal combustion engine  12  to the transmission  16  without assistance from the latching friction clutch  26 . It is to be appreciated that the one-way clutch  22  may be configured to deliver more than the first rotational torque to the transmission  16 . Said differently, the one-way clutch  22  may be over-sized such that a safety margin exists to ensure that all of the first rotational torque may be delivered by the one-way clutch  22 . 
     Alternatively, the one-way clutch  22  may be configured to deliver less than 100% of the first rotational torque from the crankshaft  14  to the transmission  16 . In this embodiment, the one-way clutch  22  in combination with the latching friction clutch  26  is required to deliver the first rotational torque from the internal combustion engine  12  to the transmission  16 . Said differently, both the one-way clutch  22  and the latching friction clutch  26  must be in the engaged state to deliver all of the first rotational torque to the transmission  16  in this embodiment. 
     In some embodiments, in the engaged state, the latching friction clutch  26  and the one-way clutch  22  are together configured to deliver from 90 to 185% of the first rotational torque from the crankshaft  14  to the transmission  16 . In other embodiments, in the engaged state, the latching friction clutch  26  and the one-way clutch  22  are together configured to deliver from 95 to 120% of the first rotational torque from the crankshaft  14  to the transmission  16 . In these embodiments, the latching friction clutch  26  and the one-way clutch  22  may be both in the engaged state to deliver all of the first rotational torque to the transmission  16 . It is to be appreciated that this range is merely exemplary. For example, the latching friction clutch  26  and the one-way clutch  22  may be together configured to deliver less than 90%, or may be together configured to deliver more than 185%, of the first rotational torque to the transmission  16 . 
     In the embodiments where the latching friction clutch  26  and the one-way clutch  22  are together configured to deliver over 100% of the first rotational torque to the transmission  16 , an additional percentage over 100% is the safety margin that exists to ensure that all of the first rotational torque is able to be delivered to the transmission  16 . The factors that determine the safety margin (i.e., the amount of the additional percentage over 100%) include, but are not limited to, the absolute amount of the first rotational torque and the ability of the one-way clutch  22  and the latching friction clutch  26  to deliver torque relative to one another. 
     The hybrid-vehicle system  10  may also include a controller  40  configured to change delivery of the first rotational torque to through the one-way clutch  22  to the transmission  16 , from through the latching friction clutch  26  to the transmission  16 . Said differently, the controller  40  changes delivery of the torque from the latching friction clutch  26  to the one-way clutch  22 . The controller  40  may change delivery of the torque upon receiving sensory input of the torque being delivered from the internal combustion engine  12  through the crankshaft  14  to the latching friction clutch  26 . It is to be appreciated that the controller  40  may also change delivery of the torque from the one-way clutch  22  to the latching friction clutch  26 . In some embodiments, the controller  40  is configured to change delivery of the first rotational torque upon the internal combustion engine  12  reaching a predetermined operating condition. The predetermined operating condition may be, but is not limited to, a portion of the first rotational torque generated by the internal combustion engine  12 , and a rotational speed of the crankshaft  14 . 
     In some embodiments, as shown in  FIGS. 1A-2B , the latching friction clutch  26  has a friction clutch input  30  that is rotationally coupled to the internal combustion engine  12 , and a friction clutch output  32  that is rotationally coupled to the electric machine  20 . The friction clutch input  30  and the friction clutch output  32  are rotationally decoupled when the latching friction clutch  26  is in the disengaged state, and the friction clutch input  30  and the friction clutch output  32  are rotationally coupled when the latching friction clutch  26  is in the engaged state. 
     In one embodiment, as shown in  FIGS. 1A and 1B , the one-way clutch  22  has a one-way clutch input  34  that is rotationally coupled to the internal combustion engine  12 , and a one-way clutch output  36  that is rotationally coupled to the electric machine  20 . In this embodiment, the friction clutch output  32  and the one-way clutch output  36  may be rotationally coupled to one another. It is to be appreciated that the one-way clutch  22  may have a one-way clutch output  36  that is rotationally coupled to the transmission  16  without being rotationally coupled to the electric machine  20 , as shown in  FIGS. 2A and 2B . In this embodiment, the friction clutch output  32  and the one-way clutch output  36  may be rotationally decoupled from one another. 
     In one embodiment, the friction clutch input  30  and the one-way clutch input  34  are both rotationally coupled to the internal combustion engine  12 , and the friction clutch output  32  and the one-way clutch output  36  are both rotationally coupled to the electric machine  20 . In this embodiment, the first rotational torque may be delivered from the internal combustion engine  12  through either the latching friction clutch  26 , the one-way clutch  22 , or both the latching friction clutch  26  and the one-way clutch  22  to the transmission  16 , and the electric machine  20  may deliver the second rotational torque directly to the transmission  16  in conjunction with the first rotational torque from the internal combustion engine  12 . 
     A method for controlling the assembly  18  for the hybrid-vehicle system  10  includes the step of engaging the latching friction clutch  26 . The step of engaging the latching friction clutch  26  is accomplished by moving the latching friction clutch  26  from the disengaged state to the engaged state. In the engaged state, the crankshaft  14  and the electric machine  20  are rotationally coupled to deliver rotational torque from the crankshaft  14  through the latching friction clutch  26  to the transmission  16 . In the disengaged state, the crankshaft  14  and the electric machine  20  are rotationally decoupled and the first rotational torque from the crankshaft  14  is not transmitted through the latching friction clutch  26 . The method also includes the step of latching the friction clutch such that the latching friction clutch remains in the engaged state. The step of latching the latching friction clutch  26  may be accomplished through moving the latch  38  of the latching friction clutch  26 , if present. The method also includes the step of engaging the one-way clutch  22  to rotationally couple the crankshaft  14  and the transmission  16  to deliver rotational torque from the crankshaft  14  through the one-way clutch  22  to the transmission  16 . 
     The method may also include the step of disengaging the latching friction clutch  26  by moving the latching friction clutch  26  from the engaged state to the disengaged state. In this embodiment, the one-way clutch  22  may still be in the engaged state and the first rotational torque may be delivered from the internal combustion engine  12  to the transmission  16 . In this embodiment, the hybrid-vehicle system  10  has reduced power consumption because the pump and/or solenoid are turned off. 
     The method may further include the step of delivering the second rotational torque via the electric machine  20  directly to the transmission  16 . Delivering the second rotational torque directly to the transmission  16  more efficiently propels the vehicle without being hindered by a damper or additional componentry. 
     In some embodiments, the step of engaging the latching friction clutch  26  precedes the step of delivering the second rotational torque via the electric machine  20  directly to the transmission  16 . In these embodiments, the second rotational torque may be supplemental to the first rotational torque from the internal combustion engine  12 . Alternatively, in other embodiments, the step of delivering the second rotational torque via the electric machine  20  directly to the transmission  16  precedes the step of engaging the latching friction clutch  26 . In these other embodiments, the electric machine  20  may be operated while the internal combustion engine  12  is not operating. 
     In some embodiments, the step of delivering the second rotational torque via the electric machine  20  directly to the transmission  16  precedes the step of engaging the one-way clutch  22 . In these embodiments, the first rotational torque may be delivered from the internal combustion engine  12  through the latching friction clutch  26  in the engaged state to the transmission, and the electric machine  20  may supplement the first rotational torque by delivering the second rotational torque to the transmission  16 . The delivery of the first and second rotational torques may be accomplished during start-up of the internal combustion engine  12  before the one-way clutch  22  is in the engaged state to deliver all of the first rotational torque to the transmission  16 . 
     In some embodiments, the step of delivering the second rotational torque via the electric machine  20  precedes the step of disengaging the latching friction clutch  26 . The latching friction clutch  26  may be disengaged during steady-state operation of the internal combustion engine  12  when the first rotational torque is being delivered from the internal combustion engine  12  through the one-way clutch  22  to the transmission  16 . As such, the electric machine  20  may be required to deliver the second rotational torque during start-up of the internal combustion engine  12 , which precedes the step of disengaging the latching friction clutch  26  during steady-state operation of the internal combustion engine  12 . 
     The method may further include the step of delivering the first rotational torque from the internal combustion engine  12  to the transmission  16 . The step of delivering the second rotational torque via the electric machine  20  directly to the transmission  16  may precede the step of delivering the first rotational torque from the internal combustion engine  12  to the transmission  16 . In this embodiment, the internal combustion engine  12  is operated before the electric machine  20  is operated. 
     The invention has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings, and the invention may be practiced otherwise than as specifically described.