Hybrid vehicle with dual clutch transmission

A vehicle includes an engine that generates an engine torque and a motor that generates a motor torque. A transmission can receive the engine torque, the motor torque, or both. The transmission includes a first gear set and a second gear set, as well as a first clutch that at least partially engages to transfer torque to the gears in the first gear set and a second clutch that at least partially engages to transfer torque to the gears in the second gear set. A controller can control the engine torque and the motor torque to control a speed of the engine to follow a desired speed profile. The controller can also control the engagement of the first clutch and the second clutch to optimize a desired gear state to minimize system losses.

TECHNICAL FIELD

The invention relates to control of a hybrid vehicle with a dual clutch transmission.

BACKGROUND

Passenger and commercial vehicles may include a transmission that transfers torque from an engine to wheels of the vehicle. A clutch or torque converter may be engaged to transfer torque from the engine to the transmission. The engagement of the clutch may be manual (e.g., actuated by a driver of the vehicle) while the torque converter may automatically transfer torque from the engine to the transmission.

SUMMARY

An example vehicle includes an engine that can generate an engine torque and a motor that can generate a motor torque. The vehicle further includes a transmission configured to receive the engine torque, the motor torque, or both, and has a plurality of gears arranged in a first gear set and a second gear set. The transmission has a first clutch configured to at least partially engage to transfer torque from at least one of the engine and the motor to the gears in the first gear set and a second clutch configured to at least partially engage to transfer torque from the engine and the motor to the gears in the second gear set. Additionally, the vehicle includes a controller configured to control the engine torque and the motor torque to control a speed of the engine to follow a desired speed profile. The controller is further configured to control the engagement of the first clutch and the second clutch to optimize a desired gear state to minimize system losses.

An example method of controlling a hybrid vehicle with a dual clutch transmission includes receiving an acceleration request, determining a clutch state, determining a desired gear state, and generating a first clutch control signal and a second clutch control signal based at least in part on the desired gear state. The method also includes generating an engine torque control signal and a motor torque control signal based at least in part on the desired gear state.

Another example method of controlling a hybrid vehicle with a dual clutch transmission includes receiving a shift command and at least partially disengaging a first clutch in response to receiving the shift command. Moreover, the method includes reducing a motor torque generated by a motor, synchronizing a second clutch, increasing the motor torque, disengaging the first clutch, and at least partially engaging the second clutch.

A hybrid vehicle having the transmission and controller disclosed herein provides greater efficiencies over other types of transmissions used in hybrid vehicles.

DETAILED DESCRIPTION

A hybrid vehicle having a dual clutch transmission is disclosed. The vehicle may take many different forms and include multiple and/or alternate components and facilities. While an example vehicle is shown in the Figures, the components illustrated in the Figures are not intended to be limiting. Indeed, additional or alternative components and/or implementations may be used.

The vehicle100may include an engine105, a motor110, a power source115, a dual clutch transmission120, a fluid reservoir125, and a controller135. The vehicle100may include any passenger or commercial automobile such as a hybrid electric vehicle including a plug-in hybrid electric vehicle (PHEV) or an extended range electric vehicle (EREV), a gas-powered vehicle, a battery electric vehicle (BEV), or the like.

The engine105may include any device configured to generate an engine torque by, for instance, burning a mixture of a fossil fuel and air. For instance, the engine105may be an internal combustion engine configured to output torque via a crankshaft140. The operation of the engine105may be controlled via an engine control unit145. The engine control unit145may be any device configured to receive command signals and control the operation of the engine105based on the command signals received. For instance, the engine control unit145may be configured to the amount of fuel and air provided into a chamber of the engine105, as well as the timing of the combustion of the fuel and air mixture.

The motor110may include any device configured to convert electrical energy into rotational motion. For instance, the motor110may be configured to receive electrical energy from the power source115and rotate an output shaft150in accordance with the electrical energy received. The rotation of the output shaft150may provide a motor torque to, for instance, the engine105and/or the transmission120. The vehicle100may include a belt155configured to transfer torque from the motor110to the engine105, and vice versa. Moreover, the motor110may be configured to receive the engine torque from the engine105in a way that allows the motor110to act as a generator. When acting as a generator, the motor110may be configured to generate electrical energy that may be stored in the power source115. The operation of the motor110may be controlled by a motor control unit160. The motor control unit160may include any electronic device configured to control, for example, the speed of rotation of the output shaft150. In one possible implementation, the motor control unit160may receive command signals and control the operation of the motor110based on the received command signals.

The power source115may include any device configured to store electrical energy and output the electrical energy to the motor110. The power source115may be further configured to receive and store electrical energy that may be generated by the motor110. In one possible implementation, the power source115may include one or more batteries. Although not illustrated, an inverter may be operatively disposed between the power source115and the motor110to convert direct current energy stored by the power source115into alternating current energy used to operate the motor110. Moreover, the inverter may be further configured to convert alternating current energy generated by the motor110into direct current energy for storage in the power source115.

The dual clutch transmission120may include any device configured to convert the engine torque, the motor torque, or both, from one torque to another torque. For instance, the transmission120may include an input shaft165, an output shaft170, a gearbox175, and a clutch assembly190. The input shaft165may include any device configured to rotate upon receipt of the engine torque and/or the motor torque. The output shaft170may include any device configured to provide a torque that may be used to rotate the wheels180of the vehicle100, and thus, propel the vehicle100. The gearbox175may include a plurality of gears that may be configured to convert the engine and/or motor torque provided to the input shaft165to the torque provided to the wheels180to propel the vehicle100. In one possible implementation, the gears within the gearbox175may be separated into a first gear set205and a second gear set210, as described in greater detail below with respect toFIG. 2. Moreover, as discussed with respect toFIG. 2, the clutch assembly190may include two clutches to control the transfer of torque between the crankshaft140and the input shaft165. Further, some components in the transmission120may be hydraulically or electrically operated, as described below with respect toFIG. 2. The operation of the transmission120may be controlled via a transmission control unit185.

The fluid reservoir125may include any device configured to store a fluid that may be used, for instance, to hydraulically actuate components of the transmission120. In one possible approach, a pump130may be used to pressurize the fluid prior to providing the fluid to the transmission120.

The controller135may include any device configured to control the motor torque and the engine torque that is provided to the transmission120. For example, the controller135may be configured to generate a command signal that causes the motor110, the engine105, or both, to rotate at a speed that generates a commanded torque. The controller135may be configured to output signals to the engine control unit145to control the engine torque and the motor control unit160to control the motor torque.

The controller135may be further configured to control the operation of one or more components of the transmission120by, for instance, generating and transmitting command signals to the transmission control unit185. For instance, the controller135may be configured to selectively engage one or more gears in the gearbox175and control the engagement of one or more clutches (seeFIG. 2) in the transmission120.

To control the transmission120, the controller135may be further configured to identify a shift action. For instance, the controller135may be configured to determine a gear selection by a driver of the vehicle100. The gear selection may indicate the driver's intention to place the vehicle100in a “park,” “reverse,” “neutral,” or “drive” operating mode. The driver may make such a gear selection using a shift lever operatively disposed in a passenger compartment of the vehicle100. The controller135may identify the gear selection and control the transmission120accordingly. Further, when in the “drive” operating mode, the controller135may be configured to monitor the speed of the vehicle100and the position of an accelerator pedal disposed in the passenger compartment and operated by the driver to determine which gears of the gearbox175to engage.

The controller135may be configured to cause the engine and/or motor torque to be transferred to the gearbox175by at least partially engaging clutches disposed in the transmission120. The controller135may be configured to synchronize one or more of the clutches prior to engaging the clutch, resulting in a smoother transition between gears during gearshifts. Moreover, the controller135may be configured to control the operation of the engine105and/or the motor110during gearshifts. For instance, the controller135may be configured to reduce the motor torque by a predetermined amount in addition to controlling the operation of the clutches (e.g., seeFIG. 7).

The controller135may be configured to use various data when controlling the operation of the engine105, the motor110, and/or the transmission120. As discussed above, the controller135may be configured to use the position of the accelerator pedal, a gear selection, and the speed of the vehicle100. Moreover, the controller135may be configured to determine a clutch state (e.g., a launch state, a declutch state, and a drive state, etc.) and command the motor torque and the engine torque based at least in part on the determined clutch state. Further, the controller135may be configured to control the engagement of one or more clutches in the transmission120based on the determined clutch state.

In one possible approach, the controller135may be further configured to control the torque transferred from the engine105to the motor110, and vice versa. For instance, the controller135may be configured to cause the motor110to transfer torque to the engine105to, for instance, reduce the load on the engine105to reduce the chance of the engine105stalling during a gearshift. The controller135may be also configured to cause the engine105to transfer torque to the motor110to, for example, cause the motor110to generate electrical energy for storage in the power source115.

FIG. 2illustrates an example dual clutch transmission120that may be used in the vehicle100. As illustrated, the transmission120includes the input shaft165, the output shaft170, and a gearbox175that includes a first gear set205and a second gear set210. Further, the transmission120includes a clutch assembly190that has a first clutch215and a second clutch220.

The first gear set205and the second gear set210may include a plurality of gears that are configured to change the rotational speed of the output shaft170relative to the input shaft165. Both the first and second gear sets205,210may include several gears of varying ratios. In one possible approach, the first gear set205may include the “even” drive gears (e.g., 2ndgear, 4thgear, and 6thgear) while the second gear set210may include the “odd” drive gears (e.g., 1stgear, 3rdgear, and 5thgear). This way, the transmission120switches between the first gear set205and the second gear set210during operation of the vehicle100. One of the first gear set205and the second gear set210may include a reverse gear.

The first clutch215and the second clutch220may each include any device configured to transfer torque from the crankshaft140of the engine105and/or the output shaft150of the motor110to the input shaft165of the transmission120. For example, the first clutch215and the second clutch220may each include a driving mechanism225and a driven mechanism230. The driving mechanism225may be operatively connected to the crankshaft140and/or the output shaft150of the motor110while the driven mechanism230may be operatively connected to the input shaft165of the transmission120.

The first clutch215and the second clutch220may be configured to actuate electrically, electromagnetically, electromechanically, hydraulically, etc. For instance, the controller135may control a valve that causes pressurized fluid to flow to one or both of the first clutch215and the second clutch220. Alternatively, the controller135may generate a command signal and transmit the command signal to the transmission control unit185. The transmission control unit185may cause the pressurized fluid to flow to one or both of the first clutch215and the second clutch220. Upon receipt of the pressurized fluid, the first clutch215or the second clutch220may at least partially engage (e.g., the driving mechanism225may be at least partially engaged with the driven mechanism230).

When at least partially engaged, the driving mechanism225may transfer at least a portion of the engine torque and/or the motor torque to the input shaft165of the transmission120. When partially engaged, the driving mechanism225and the driven mechanism230may slip relative to one another. That is, the driving mechanism225and the driven mechanism230may rotate at different speeds. When fully engaged, the driving mechanism225and the driven mechanism230may rotate at substantially the same speeds. When disengaged, the driving mechanism225and the driven mechanism230may be free to rotate at different speeds. When the first clutch215is at least partially engaged, the engine torque and/or the motor torque is transferred to the first gear set205, and when the second clutch220is at least partially engaged, the engine torque and/or the motor torque is transferred to the second gear set210.

FIG. 3illustrates an example control architecture that may be used by the controller135to control the motor torque, the engine torque, the engagement of the first clutch215, and the engagement of the second clutch220.

At block300, the controller135may receive the position of the accelerator pedal. For instance, the driver may press the accelerator pedal in the passenger compartment, and the controller135may determine the driver's intent to operate the vehicle100based on the way that the driver presses the accelerator pedal. The controller135may generate an output torque request based on the position of the accelerator pedal.

At block305, the controller135may receive the position of the accelerator pedal, the output torque request, the current gear, and the speed of the vehicle100. The controller135may use this information to determine a clutch state, such as a launch state, a declutch state, or a drive state. The launch state may indicate that the driver intends to launch the vehicle100. The declutch state may indicate that one or both of the first clutch215and the second clutch220should be disengaged. The drive state indicates that the vehicle100is in the “drive” operating mode.

At block310, the controller135may receive the output torque request, the speed of the vehicle100, a state of charge of the power source115, and the clutch state determined at block305. With this information, the controller135may determine a desired engine torque, a desired motor torque, and a desired gear.

At block315, the controller135may receive the desired gear and determine the amount of torque to transfer across the first clutch215and the second clutch220. The controller135may be configured to output one or more command signals to control the engagement of the first clutch215and/or the engagement of the second clutch220. The controller135may transmit the command signals to the transmission control unit185, which may actuate one or more valves, such as one or more solenoid valves, to control the flow of the pressurized fluid to the first clutch215and/or the second clutch220. Alternatively, the controller135may transmit the command signals directly to the solenoid valves to control the flow of the pressurized fluid to the first clutch215and/or the second clutch220.

Additionally, at block315, the controller135may further determine an engine torque intervention and a motor torque intervention, which may be used to modify the desired engine torque determined at block310and the desired motor torque determined at block310, respectively, to provide a smoother gear shift. The controller135may generate command signals to control the engine105to generate the engine torque and the motor110to generate the motor torque based on the modified desired engine and motor torque, respectively, and output the command signals to the engine control unit145and the motor control unit160.

FIG. 4illustrates an example control architecture that may be used by the controller135to control the vehicle100during launch.

At block400, the controller135may receive the position of the accelerator pedal that may be operably disposed within the passenger compartment of the vehicle100. The controller135may output a torque output request based on the position of the accelerator pedal.

At block405, the controller135may consider the currently engaged gear of the transmission120and the torque output request to determine a desired crankshaft torque. The desired crankshaft torque may be output to block430to determine a speed of the engine105and used to determine to a crankshaft torque command after block435.

At block410, the controller135may receive the position of the accelerator pedal and determine an electrical launch k-factor. The k-factor may describe the stall speed of the motor110divided by the square root of the motor torque at the stall speed.

At block415, the controller135may receive the position of the accelerator pedal and determine an engine-only or engine on launch k-factor. In this context, the k-factor may describe the stall speed of the engine105divided by the square root of the engine torque at the stall speed.

At decision block420, the controller135may determine which k-factor to apply using, for example, the torque output request, the state of charge of the power source115, the electrical launch k-factor determined at block410, the engine-on launch k-factor determined at block415, etc. The k-factor may be determined based on the operating mode of the vehicle100. For instance, when operating in an electrical-only mode (e.g., only the motor110is providing torque to the transmission120), the controller135may select the electrical launch k-factor. If, however, the engine105is providing torque to the transmission120, the controller135may select the engine-on launch k-factor.

At block425, the controller135may determine whether to modify the k-factor selected at block420. That is, if the vehicle100is operating in a way such that both the motor110and engine105are providing a torque to the transmission120, the controller135may determine a blended k-factor to apply. The blended k-factor may be output to block430.

At block430, the controller135may determine a desired input shaft speed (e.g., the speed of the input shaft165of the transmission120) based on the desired crankshaft140speed and the blended or selected k-factor. This implementation described with reference to blocks410,415,420,425, and430is one way to generate the engine speed profile. Other ways of generating the engine speed profile may be used as an alternative to that described above.

At block435, the controller135may receive the current speed of the input shaft165and the desired speed of the input shaft165determined at block430and output an inertial torque, which may be added to the desired crankshaft torque to generate the crankshaft torque command. The crankshaft torque command may be output to control the first clutch215, the second clutch220, or both, such that the torque commanded by the crankshaft torque command is transferred through the first clutch215, the second clutch220, or both, to the transmission120.

At block440, the controller135may determine a torque split optimization based on the crankshaft torque command and system losses for each available gear state. The controller135may determine a power loss for two or more “drive” gears of the transmission120based on the crankshaft torque command and the system losses. System losses include such things as engine losses, transmission and driveline losses, motor and inverter losses, and battery system losses, etc. Moreover, the controller135may output a commanded engine torque (e.g., via an engine torque command signal) that may be output to the engine control unit145and a commanded motor torque (e.g., via a motor torque command signal) that may be output to the motor control unit160.

At block445, the controller135may optimize the power loss during launch based on the power loss and commanded engine torque and motor torque determined at block440. That is, the controller may select the gear state with the commanded engine and motor torque that provides minimal power loss, which is the output from block440. The controller135may output a desired gear, an optimized motor torque, and an optimized engine torque to control the first clutch215, the second clutch220, the motor110, and the engine105during launch.

FIG. 5illustrates an example control architecture that may be used by the controller135to control the operation of the vehicle100during a declutch state (e.g., a state where one or both of the first clutch215and the second clutch220are disengaged).

At block500, the controller135may determine an acceleration request based on a position of the accelerator pedal and generate a torque output request based on the position of the accelerator pedal.

At block505, the controller135may receive the torque output request determined at block500along with a gear number indicating the currently engaged “drive” gear. The controller135may output a desired crankshaft torque based on the currently engaged gear and the output torque request.

At block510, the controller135may receive an operating state such as an “engine105off/electrical spintrol off” state, an “engine105off/electrical spintrol on” state, or an “engine105on idle” state. At block510, the controller135may further receive a current speed of the input shaft165of the transmission120. The controller135may apply the operating state and current speed of the input shaft165to a desired clutch slip profile and output a speed. The term “spintrol” may refer to the motor110maintaining the speed of an unfuelled engine105at a low (e.g., idle) speed to maintain zero lash in the powertrain to avoid a clunk upon a driver accelerator pedal input.

At block515, the controller135may receive the current speed of the input shaft165summed with the speed determined based on the desired clutch slip profile at block510, which may be the desired speed of the input shaft165. The controller135may determine an inertial torque of the motor110and/or engine105based on the desired speed of the input shaft165. The inertial torque of the motor110and/or engine105may be summed with the desired crankshaft torque to generate a crankshaft torque command that may be output to control either the first clutch215, the second clutch220, or both.

At block520, the controller135may determine a torque split optimization based on the crankshaft torque command and system losses. The controller135may determine a power loss for two or more “drive” gears of the transmission120based on the crankshaft torque command and the system losses. Moreover, the controller135may output a commanded engine torque (e.g., via an engine torque command signal) that may be output to the engine control unit145and a commanded motor torque (e.g., via a motor torque command signal) that may be output to the motor control unit160.

At block525, the controller135may select the declutch state with the commanded engine and motor torque that provides minimal power loss, which is the output from block520. The controller135may output a desired gear, an optimized motor torque, and an optimized engine torque to control the first clutch215, the second clutch220, the motor110, and the engine105during a declutch state.

FIG. 6illustrates an example control architecture that may be used by the controller135to control the operation of the vehicle100during a drive state.

At block600, the controller135may determine an acceleration request based on a position of the accelerator pedal and output a torque output request based at least in part on the position of the accelerator pedal.

At block605, the controller135may receive the torque output request determined at block600along with a gear number indicating the currently engaged “drive” gear. The controller135may output a desired crankshaft torque and a desired speed of the input shaft165based on the currently engaged gear and the output torque request. The desired crankshaft torque may be used to generate a crankshaft torque command that may be used to control the first clutch215, the second clutch220, or both.

At block610, the controller135may determine a torque split optimization based on the crankshaft torque command and system losses. The controller135may determine a power loss for two or more “drive” gears of the transmission120based on the crankshaft torque command and the system losses. Moreover, the controller135may output a commanded engine torque (e.g., via an engine torque command signal) that may be output to the engine control unit145and a commanded motor torque (e.g., via a motor torque command signal) that may be output to the motor control unit160.

At block615, the controller135may select the drive state with the commanded engine and motor torque that provides minimal power loss, which is the output from block610. The controller135may output a desired gear, an optimized motor torque, and an optimized engine torque to control the first clutch215, the second clutch220, the motor110, and the engine105during a drive state.

FIG. 7illustrates an example graph700of the speed720of the engine105, the clutch pressure725of the off-going clutch, which may be the first or second clutch215,220, the clutch pressure730of the on-coming clutch, which may be the first or second clutch215,220, and the output torque735, the engine torque740, and the motor torque745at various periods of time (e.g., time705,710, and715) relative to a shift event.

Prior to time705, the first clutch215may be engaged, the speed720of the engine105may increase, and the engine torque740and the motor torque745may be combined to provide the output torque735. The controller135may be configured to identify a shift event, which may occur sometime prior to time705.

A speed phase may begin at time705. During the speed phase, the pressurized fluid provided to the off-going clutch may be reduced to a critical pressure, causing the off-going clutch to partially disengage (e.g., slip) for a predetermined amount of time as indicated by the line725. While slipping the off-going clutch, the motor torque is reduced to bring engine speed down to synchronize. Also, the motor torque745may be reduced. Before the end of the speed phase, the second clutch220may be synchronized and the motor torque745may be increased to approximately the same torque as before time705.

A torque phase may begin at time710. During the torque phase, the off-going clutch may be disengaged while the on-coming clutch is engaged as indicated by lines725and730. The on-coming clutch may transfer the motor torque745and/or the engine torque740to different gears than the first clutch215, resulting in a change in the ratio of the speed of the input shaft165to change relative to the speed of the output shaft170. Therefore, during the torque phase, the output torque735of the vehicle100(e.g., the torque of the output shaft170of the transmission120) and the speed720of the engine105may change when the on-coming clutch pressure730ramps up. InFIG. 7, the illustrated output torque735drops slightly while the speed720of the engine105rises slightly.

At the conclusion of the torque phase (e.g., at time715), the on-coming clutch may be fully engaged as indicated by line730. The speed720of the engine105continues to rise after time715and the output torque735will be at a reduced level relative to the output torque735during the speed phase (e.g., between times705and710) due to the change in the transmission ratio. The engine torque740and the motor torque740may remain relatively constant after the torque phase (e.g., after time715).

FIG. 8illustrates an example process800that may be implemented by the controller135to control the operation of the vehicle100.

At block805, the controller135may receive an acceleration request. For instance, the controller135may receive a signal from a sensor operatively disposed on or near the accelerator pedal indicating that the driver intends to increase or decrease the speed of the vehicle100. For instance, if the driver pushes on the accelerator pedal, the controller135may receive a signal indicating that the driver intends for the speed of the vehicle100to increase. If the driver releases or lets up on the accelerator pedal, the controller135may receive a signal indicating that the driver intends for the vehicle100to coast or slow down.

At block810, the controller135may determine a clutch state. The clutch state may be a launch state, a declutch state, a drive state, etc. The clutch state may indicate the engagement and/or disengagement of the first clutch215, the second clutch220, or both.

At block815, the controller135may determine a desired gear state. The desired gear state may be a gear that provides an appropriate torque conversion between the input shaft165and the output shaft170of the transmission120. The desired gear state may be based on the position of the accelerator pedal determined at block805and the clutch state determined at block810. The desired gear state may be further based on the current gear state and the speed of the vehicle100.

At block820, the controller135may generate one or more clutch control signals based on the desired gear state. For instance, a first clutch control signal may be used to control the first clutch215and a second clutch control signal may be used to control the second clutch220. That is, the first clutch control signal may be used to command the first clutch215to at least partially engage to transfer torque from the motor110, the engine105, or both, through the first gear set205of the transmission120. The second clutch control signal may be used to command the second clutch220to at least partially engage to transfer torque from the motor110, the engine105, or both, through the second gear set210of the transmission120.

At block825, the controller135may generate one or more torque control signals to control the operation of the engine105and/or the motor110based on the desired gear state. For instance, the controller135may generate the engine torque control signal to command the engine105to provide the engine torque to the transmission120. The controller135may generate the motor torque control signal to command the motor110to provide the motor torque to the transmission120.

FIG. 9illustrates an example process900that may be implemented by the controller135to control the operation of the first clutch215and the second clutch220during a shift action.

At block905, the controller135may receive a shift command. The controller135may generate a shift command indicating when to shift gears of the transmission120based on, for instance, the position of the accelerator pedal, the current speed of the vehicle100, the currently engaged gear, etc.

At block910, the controller135may at least partially disengage the first clutch215in response to receiving the shift command. When at least partially disengaged, the first clutch215may transfer some torque from the engine105and/or motor110to the transmission120. However, the driven mechanism230of the first clutch215may slip relative to the driving mechanism225.

At block915, the controller135may reduce the motor torque generated by the motor110. Reducing the motor torque alone or in combination with at least partially disengaging the first clutch215may allow the speed of the crankshaft140to slow. In one possible approach, the motor torque may be reduced at or about the same time that the controller135at least partially disengages the first clutch215. This example approach at block915represents an upshift. For a downshift, the input speed may be increased to synchronize the first clutch215.

At block920, the controller135may synchronize the second clutch220. For instance, the controller135may cause the driving mechanism225and the driven mechanism230of the second clutch220to rotate at similar speed prior to engaging the second clutch220.

At block925, the controller135may increase the motor torque. In one possible implementation, the motor torque may be increased prior to synchronizing the second clutch220.

At block930, the controller135may disengage the first clutch215. For instance, the controller135may fully disengage the first clutch215so that the first clutch215transfers no torque to the transmission120from the engine105, the motor110, or both.

At block935, the controller135may at least partially engage the second clutch220. For instance, the controller135may engage the driving mechanism225and the driven mechanism230of the second clutch220so that the second clutch220transfers torque to the transmission120from the engine105, the motor110, or both. In one possible approach, the controller135may disengage the first clutch215and engage the second clutch220at or about the same time. This way, the transmission may always receive torque from the engine and/or motor.