초록 ▼

An electro-mechanical transmission is provided having only a single motor/generator, at least one differential gear set and two torque-transmitting mechanisms. A first of the torque-transmitting mechanisms is selectively engageable to establish a first continuously variable operating mode and a seco

An electro-mechanical transmission is provided having only a single motor/generator, at least one differential gear set and two torque-transmitting mechanisms. A first of the torque-transmitting mechanisms is selectively engageable to establish a first continuously variable operating mode and a second of the torque-transmitting mechanisms selectively engageable to establish a second continuously variable operating mode and a synchronous shift between the two operating modes is achievable. A method of control is provided in which vehicle operating characteristics are analyzed to identify a target operating state in terms of operating mode and ratio based on the available motor torque and motor power and on maximizing energy efficiency. The transmission is controlled to approach this operating mode as closely as possible and the diverge away from the optimum torque operating with zero net battery use as the battery charge of the battery connected with the motor/generator accumulates or depletes.

대표청구항 ▼

The invention claimed is: 1. An electro-mechanical transmission comprising: an input member to receive power from an engine; an output member for delivering power from the transmission; a single motor/generator, wherein the transmission is characterized by an absence of another motor/generator affe

The invention claimed is: 1. An electro-mechanical transmission comprising: an input member to receive power from an engine; an output member for delivering power from the transmission; a single motor/generator, wherein the transmission is characterized by an absence of another motor/generator affecting power flow between the input member and the output member; at least one differential gear set having a plurality of members including at least a first member, a second member and a third member; wherein said input member, said output member and said motor/generator are each operatively connectable with different ones of said members of said at least one differential gear set; a first torque-transmitting mechanism selectively engageable to establish a first continuously variable operating mode characterized by a first range of speed ratios; and a second torque-transmitting mechanism selectively engageable to establish a second continuously variable operating mode characterized by a second range of speed ratios; wherein engagement of one of said first and second torque-transmitting mechanisms and disengagement of the other of said first and second torque-transmitting mechanisms to shift between said respective continuously variable operating modes can be accomplished with essentially zero relative speed across both of said torque-transmitting mechanisms while both of said input member and output member are rotating. 2. The electro-mechanical transmission of claim 1, wherein engagement of said first torque-transmitting mechanism operatively connects said single motor/generator with one of said members of said at least one differential gear set; and wherein engagement of said second torque-transmitting mechanism operatively connects said single motor/generator with another of said members of said at least one differential gear set. 3. The electro-mechanical transmission of claim 1, wherein said at least one differential gear set is a simple planetary gear set. 4. The electro-mechanical transmission of claim 3, wherein said at least one differential gear set is representable by a first lever of a lever diagram having a first, a second and a third node; wherein said first torque-transmitting mechanism is a first clutch selectively engageable to connect the input member with said first node, wherein said second torque-transmitting mechanism is a second clutch selectively engageable to connect the input member with said second node, wherein the motor/generator is operatively connected with said third node; and further comprising: a third clutch selectively engageable to operatively connect said output member with said second node; a fourth clutch selectively engageable to operatively connect said output member with said first node; and a first brake selectively engageable to ground said third node to a stationary member; wherein said first and third clutches are engaged to establish said first continuously variable operating mode, wherein said second and fourth clutches are engaged to establish said second continuously variable operating mode; and wherein said first clutch, said third clutch and said brake are engaged to establish a first fixed forward speed ratio, wherein a second fixed forward speed ratio is established either by engagement of only one of said first and second clutches and both of said third and fourth clutches or by engagement of both of said first and second clutches and only one of said third and fourth clutches, and wherein said second clutch, said fourth clutch and said brake are engaged to establish a third fixed forward speed ratio. 5. The electro-mechanical transmission of claim 1, wherein said at least one differential gear set is representable by a first level of a lever diagram having a first, a second, a third and a fourth node; wherein said input member is operatively connectable with said first node; wherein said output member is continuously connected with said second node; wherein engagement of said first torque-transmitting mechanism connects said motor/generator with said third node; and wherein engagement of said second torque-transmitting mechanism connects said motor/generator with said fourth node. 6. The electro-mechanical transmission of claim 5, wherein said first lever is characterized by an absence of any additional nodes. 7. The electro-mechanical transmission of claim 6, wherein said first torque-transmitting mechanism is a first clutch, wherein said second torque-transmitting mechanism is a second clutch; and further comprising: a first brake selectively engageable to ground said third node to a stationary member; and a second brake selectively engageable to ground said fourth node to a stationary member; wherein engagement of said first brake establishes a first fixed forward speed ratio; wherein engagement of said first clutch and said second clutch establishes a second fixed forward speed ratio; and wherein engagement of said second brake establishes a third fixed forward speed ratio. 8. The electro-mechanical transmission of claim 6, wherein said at least one differential gear set has a first and a second planetary gear set each having a ring gear member, a sun gear member and a carrier member, and wherein said first and second planetary gear sets are compounded such that two of said members of said first planetary gear set are each continuously connected to a different respective member of said second planetary gear set. 9. The electro-mechanical transmission of claim 5, wherein said first lever further includes a fifth node. 10. The electro-mechanical transmission of claim 9, wherein said first lever is characterized by an absence of any additional nodes. 11. The electro-mechanical transmission of claim 10, wherein said first torque-transmitting mechanism is a first clutch, wherein said second torque-transmitting mechanism is a second clutch, and further comprising: a first brake selectively engageable to operatively connect said fifth node with a stationary member; a second brake selectively engageable to operatively connect said third node with said stationary member; and a third brake selectively engageable to operatively connect said fourth node with said stationary member; wherein engagement of said first brake establishes a first fixed forward speed ratio; wherein engagement of said second brake establishes a second fixed forward speed ratio; wherein engagement of said first and second clutches establishes a third fixed forward speed ratio; and wherein engagement of said third brake establishes a fourth fixed forward speed ratio. 12. The electro-mechanical transmission of claim 11, further comprising: a fourth brake selectively engageable to connect said input member with said stationary housing; wherein said first clutch and said fourth brake are engaged to establish an electric forward mode in which the transmission is powered only by said motor/generator. 13. The electro-mechanical transmission of claim 10, wherein said first torque-transmitting mechanism is a first clutch, wherein said second torque-transmitting mechanism is a second clutch; and further comprising: a first brake selectively engagable to ground said fifth node to a stationary member; a second brake selectively engagable to ground said third node to said stationary member; a third brake selectively engagable to ground said fourth node to said stationary member; and a fourth brake selectively engagable to ground said input member to said stationary member; wherein engagement of said first brake establishes a first fixed forward speed ratio; wherein engagement of said second brake establishes a second fixed forward speed ratio; wherein engagement of said first clutch and said second clutch establishes a third fixed forward speed ratio; and wherein engagement of said third brake establishes a fourth fixed forward speed ratio. 14. A method of operating an electro-mechanical transmission having an input member to receive power from an engine, an output member for delivering power from the transmission, a single motor/generator operatively connected to a battery for receiving power from the battery to act as a motor and for delivering power to the battery to act as a generator, wherein the battery is characterized by a maximum and a minimum charge, wherein the transmission is characterized by an absence of another motor/generator affecting power flow through the transmission, at least one differential gear set having a plurality of members, wherein the input member and said motor/generator are each operatively connectable with a different respective one of the members of said at least one differential gear set, a plurality of torque-transmitting mechanisms, wherein different ones of the torque-transmitting mechanisms are selectively engagable to establish different respective operating modes including at least one continuously variable mode characterized by a range of speed ratios and at least one fixed ratio mode having the same engaged torque-transmitting mechanisms as said at least one continuously variable mode, the method comprising: determining values of pre-selected vehicle operating characteristics in a current operating state of the transmission characterized by one of said operating modes, one of said speed ratios, a motor speed and a motor torque, said vehicle operating characteristics including vehicle speed, vehicle load and vehicle operator inputs; analyzing the determined values to thereby identify a target operating state characterized by one of said operating modes and one of said speed ratios and at which the vehicle will be characterized by optimal energy efficiency for said determined values; if the operating mode of the current operating state is different than the operating mode of the target operating state, engaging all of the torque-transmitting mechanisms that establish the operating mode of the target operating state and that are not engaged in the current operating state and disengaging all of the torque-transmitting mechanisms that establish the first operating state and that are not engaged in the operating mode of the target operating state to establish the operating mode of said target operating state; and controlling power flow between the battery and the motor/generator to target the speed ratio of the target operating state, thereby causing the battery to reach one of the maximum and the minimum charge and the transmission to be characterized by a fixed speed ratio established by the engaged torque-transmitting mechanisms of the operating mode of the target operating state. 15. The method of claim 14, wherein different ones of the torque-transmitting mechanisms are selectively engagable to establish at least two continuously variable operating modes including a first continuously variable operating mode and a second continuously variable operating mode; wherein the operating mode of the current operating state is one of the first and the second continuously variable mode and the operating mode of the target operating state is the other of the first and the second continuously variable mode; and wherein the engaging and disengaging steps are synchronous. 16. A method of operating an electro-mechanical transmission on a vehicle, the transmission having a single motor/generator in power flow communication with a battery and having continuously variable modes, each including a range of speed ratios, and fixed ratio modes, comprising: determining values of pre-selected vehicle operating characteristics at a current time when the vehicle is characterized by a current operating state characterized by one of said modes; analyzing the determined values to thereby identify a target operating state characterized by one of said continuously variable modes and a speed ratio within the range of speed ratios of the continuously variable mode of the target operating state; if the mode of the current operating state is different than the mode of the target operating state, changing the engaged torque-transmitting mechanisms to establish the mode of the target operating state; and controlling power flow between the battery and the motor/generator to target the speed ratio of the target operating state, thereby causing the charge of the battery to be one of a minimum and a maximum level wherein net battery power flow is zero and the transmission is therefore characterized by a fixed speed ratio established by the engaged torque-transmitting mechanisms of the target operating state. 17. The method of claim 16, wherein the continuously variable modes include a first continuously variable mode and a second continuously variable mode, said first and second continuously variable modes being established by engagement of different ones of the torque-transmitting mechanisms; wherein the operating mode of the current operating state is one of the first and the second continuously variable modes and the operating mode of the target operating state is the other of the first and the second continuously operating modes; and wherein said engaging and disengaging steps are synchronous.