Method for controlling the operation of a power machine in a multi-mode drivetrain system

Abstract

Method (200) for operating a multi-mode powertrain system comprising an electromechanical two-mode transmission (10) with combined power splitting, comprising two planetary gear sets (20, 30) and three engageable clutches (C1 52, C2 54, C3 56), configured to transmit torque between a power machine (12), two torque machines (60, 62) and an output element (92) in one of a plurality of transmission ranges, comprising a fixed gear range (Fixed Gear 1), three electric vehicle ranges (Motor 2 EV, Motor A EV, Motor B EV), two electrically variable transmission ranges (EVT Mode 1, EVT Mode 2) and a neutral range (Neutral 1 / ETC), wherein no clutches (C1 52, C2 54, C3 56) are engaged in the neutral range, wherein the method (200) responds on a fault that is associated with the operation of one (X) of the torque machines (60, 62) includes: in response to a command to disable one (X) of the torque machines (60, 62) (202), which includes a command to operate the transmission (10) in a neutral range (Neutral 1 / ETC) and a command to reduce the torque output of one (X) of the torque machines (60, 62) to a torque output of zero, converging the minimum and maximum torque capacities of one (X) of the torque machines (60, 62) to zero (204), and converging the minimum and maximum system torque limits of the power machine (12) to a single torque command to the power machine (12) in response to the minimum and maximum torque capacity limits of one (X) of the torque machines (60, 62) and an output torque request (208); and Controlling the torque output from the power machine (12), which includes applying a fast power machine actuator to control the power machine (12) in response to the output torque request, and holding the torque output from one (X) of the torque machines (60, 62) to zero (212).

Description

[0001] This disclosure relates to multi-mode powertrain systems employing multiple torque-generating devices and associated control devices for dynamic systems.

[0002] Powertrain systems can be designed to transmit torque from multiple torque actuators through a torque transmission device to an output element, which may be coupled to a final drive. Such powertrain systems include hybrid powertrain systems and extended-range electric vehicle systems. Control systems for operating such powertrain systems operate the torque actuators and employ torque transmission components in the transmission to transfer torque in response to operator-commanded output torque requests, taking into account fuel economy, emissions, drivability, and other factors. Exemplary torque actuators include internal combustion engines and non-combustion-based torque machines.Non-combustion torque machines can include electric machines that can operate as motors or generators to produce a torque input to the transmission, either in conjunction with or independently of a torque input from the internal combustion engine. These torque machines can convert the vehicle's kinetic energy, transmitted through the final drive, into electrical energy in a process known as recuperation, which can then be stored in an electrical energy storage device.A control system monitors various inputs from the vehicle and the operator and provides functional control of the hybrid powertrain, which includes controlling the transmission operating range and gear shifting, controlling the torque actuators, and regulating the electrical power exchange between the electrical energy storage device and the torque actuators to manage transmission outputs that include torque and speed.

[0003] Known electrically adjustable multi-mode transmissions (EVTs) can be configured to operate in one or more fixed-gear ranges, one or more electric vehicle (EV) ranges, one or more electrically adjustable transmission (EVT) ranges, and one or more neutral ranges. A zero torque output from one of the torque machines may be desired while operating in one of the transmission ranges due to a commanded neutral condition, in response to a reduced torque output from the torque machine, or in response to a fault associated with the operation of the torque machine.

[0004] From DE 102 36 202 A1, it is known to operate engines that tend to knock under high load conditions with a low compression ratio. However, this limits fuel economy in such frequently occurring engine operating ranges. As a compromise, the engine can be operated in a high compression ratio mode while simultaneously retarding or delaying the ignition timing from the ignition angle applicable to the maximum braking torque (MBT) in order to prevent knocking.

[0005] German patent DE 10 2011 111 395 A1 discloses that when the ignition timing of a combustion engine is set to a calibrated ignition timing, the resulting torque can be as close as possible to a mean best torque (MBT). The MBT refers to the maximum engine output torque produced for a given airflow when the ignition timing is increased while using fuel with an octane rating higher than a predetermined threshold and stoichiometric fuel delivery. The ignition timing at which this maximum torque occurs is referred to as an MBT spark. The calibrated ignition timing may differ slightly from the MBT spark, for example, due to fuel quality (e.g., when using fuel with a lower octane rating) and environmental factors.The torque during calibrated ignition advance can therefore be lower than the MBT.

[0006] DE 10 2005 030 603 A1 discloses a control device for a hybrid drive system comprising an internal combustion engine, two electric motors, and a multi-mode transmission, designed to transmit torque between a power engine, torque motors, and an output element in one of a plurality of transmission ranges. Specific control of the internal combustion engine when one of the torque motors is deactivated is not disclosed.

[0007] From DE 10 2005 006 369 A1, a method for the optimal selection of the input torque with stable power flow for a hybrid electric vehicle is known. For this purpose, power loss and cost analyses are performed for individual operating ranges. Total system power losses are calculated for permissible input torques. A solution for the input torque corresponding to the minimum total system power loss is brought to convergence in order to determine the preferred input torque.

[0008] DE 10 2007 027 965 A1 discloses a method for operating a drive unit for a hybrid vehicle. The drive unit is designed to transmit torque from an internal combustion engine and an electric machine to an output element. The method includes, in the event of a torque demand that cannot be met by the electric machine, converging the minimum and maximum torque capacities of the electric machine and controlling the torque output from the internal combustion engine. This includes the use of a fast power machine actuator to control the power machine in response to an output torque demand.

[0009] The object of the invention is to provide a method for operating a drive train system comprising an electromechanical two-mode transmission with combined power splitting, having two planetary gear sets and three engageable clutches, in the event of a fault associated with the operation of the torque machine.

[0010] This problem is solved by a method having the features of claim 1.

[0011] Advantageous embodiments are specified in the dependent claims.

[0012] The invention is described below by way of example with reference to the drawings, wherein: Fig. 1 schematically shows an embodiment of a multi-mode powertrain system comprising an internal combustion engine and a two-mode transmission, according to the disclosure; Fig.2 schematically an embodiment of a control scheme that is applied to an embodiment of the with reference to Fig. 1 to control the described drivetrain system in order to disable one of the torque machines, thereby generating zero torque from there, as shown in the disclosure; and Fig. 3 graphically defined operating parameters of an embodiment of the with reference to Fig. are assigned to the powertrain system described in 1, wherein one embodiment of the powertrain system described with reference to Fig. The control scheme described in section 2 is executed as shown in the disclosure.

[0013] Now, referring to the drawings, it shows Fig.1. A multi-mode drivetrain system according to the invention, comprising an internal combustion engine (power engine) 12, a two-mode transmission (transmission) 10, and a controller 5. The transmission 10 is mechanically coupled to torque actuators comprising the power engine 12 and a first and second torque engine 60 and 62, respectively, and is designed to transmit torque between the power engine 12, the first and second torque engines 60 and 62, and a final drive 90. The first and second torque engines 60 and 62 are electric motors / generators. The final drive 90 can comprise a differential system enabling a rear-wheel-drive vehicle configuration or a transaxle system enabling a front-wheel-drive vehicle configuration.

[0014] The engine 12 can be any suitable internal combustion engine and comprises a multi-cylinder internal combustion engine that can be selectively operated in different states to transmit torque to the transmission 10 via an input element 14. It can be a spark-ignition or compression-ignition engine. The engine 12 preferably comprises a crankshaft coupled to the input element 14 of the transmission 10. The power output of the engine 12, i.e., the engine speed and torque, can differ from the input speed and torque to the transmission 10 due to the placement of torque-consuming components at the input element 14 between the engine 12 and the transmission 10, e.g., a torque management device or a mechanically driven hydraulic pump.The power unit 12 is designed to perform auto-stop and auto-start operations during continuous operation of the powertrain in response to operating conditions. The controller 5 is designed to control actuators of the power unit 12 and thus combustion parameters, including intake air flow rate, ignition timing, injected fuel quantity, fuel injection timing, EGR valve position for controlling the flow of recirculated exhaust gases, and intake and / or exhaust valve timing and phase positions on power units so equipped. The power unit 12 employs fast power unit actuators, e.g., ignition timing control or fuel injection timing control, and slow power unit actuators, e.g., throttle / air flow control or fuel flow control, to control the torque output of the power unit.Thus, the speed and torque of the engine can be controlled by adjusting combustion parameters, including airflow torque and ignition spark-induced torque. The engine speed can also be controlled by adjusting the reaction torque at the input element 14 through the control of the engine torques of the first and second torque engines 60 and 62.

[0015] The illustrated transmission 10 is an electromechanical two-mode transmission 10 with combined power splitting, comprising two planetary gear sets 20 and 30 and three engageable torque transmission devices, i.e., clutches C1 52, C2 54, and C3 56. The two operating modes refer to power-splitting operating modes, including an input power-splitting operating mode and a combined power-splitting mode, as described herein. The planetary gear set 20 comprises a sun gear element 22, a ring gear element 26, and planet gears 24 coupled to a carrier element. The carrier element rotatably mounts the planet gears 24, which are arranged in a meshing relationship with both the sun gear element 22 and the ring gear element 26, and is coupled to a rotatable shaft element 16.The planetary gear set 30 comprises a sun gear element 32, a ring gear element 36, and planet gears 34, which are coupled to a carrier element. The planet gears 34 are arranged in a meshing relationship with both the sun gear element 32 and the ring gear element 36, and the carrier element is coupled to the rotatable shaft element 16.

[0016] As used herein, couplings refer to torque transmission devices that can be selectively engaged in response to a control signal. Each coupling can be any suitable torque transmission device, including, for example, a single or composite plate coupling or a single or composite plate pack, a one-way coupling, a band coupling, or a brake. In one embodiment, one or more of the couplings can include one-way coupling devices or selectable one-way coupling devices. A control circuit is configured to control the coupling states of each coupling, including engaging and disengaging each coupling.In one embodiment, the control circuit is a hydraulic circuit configured to control the clutch states of each of the clutches, with hydraulic pressure fluid supplied by a hydraulic pump that can be functionally controlled by the controller 5. Clutch C2 54 is a rotary clutch. Clutches C1 52 and C3 56 are brake devices that can be fixed to a gearbox 55.

[0017] An electrical high-voltage system comprises an electrical energy storage device, e.g., a high-voltage battery, which is electrically coupled to a power converter module via a high-voltage electrical bus, and is equipped with suitable devices for monitoring the electrical power flow, including devices and systems for monitoring the electrical current and voltage. The battery can be any suitable high-voltage electrical energy storage device, e.g., a high-voltage battery, and preferably includes a monitoring system that measures the electrical power supplied to the electrical high-voltage bus, which includes voltage and electrical current.

[0018] The first and second torque machines 60, 62 are, in one embodiment, three-phase motor / generator machines, each comprising a stator, a rotor, and a speed sensor, e.g., a resolver. The motor stator for each of the torque machines 60, 62 is fixed to an outer section of the gearbox 55 and comprises a stator core with helical electrical windings extending from it. The rotor for the first torque machine 60 is supported on a hub-plate gear, which is mechanically attached to a rotating element coupled to the sun gear 22 of the first planetary gear set 20. The rotor for the second torque machine 62 is fixed to a rotating element coupled to the sun gear 32 of the second planetary gear set 30.

[0019] The output element 92 of the transmission 10 is rotatably connected to the final drive 90 to supply output power to the final drive 90, which is transmitted to one or more vehicle wheels via a differential, a transaxle assembly, or another suitable device. The output power at the output element 92 is characterized in terms of output speed and output torque.

[0020] The input torque from the power machine 12 and the motor torques from the first and second torque machines 60, 62 are generated as a result of energy conversion from fuel or electrical potential stored in the electrical energy storage device (battery). The battery is high-voltage DC coupled to the power converter module via the high-voltage electrical bus. The power converter module preferably comprises a pair of power converters and respective motor control modules, which are configured to receive torque commands and control the converter states accordingly, thus providing motor drive or recuperation functionality to comply with the motor torque commands.The power converters comprise complementary three-phase power electronics, each including a plurality of insulated-gate bipolar transistors (IGBTs) for converting DC power from the battery into AC power to drive one of the first and second torque machines 60 and 62, respectively, by switching at high frequencies. The IGBTs form a switching power supply configured to receive control commands. Each phase of each of the three-phase electric machines includes a pair of IGBTs. The states of the IGBTs are controlled to provide either mechanical motor drive power generation or electrical energy recuperation functionality.The three-phase converters receive or supply direct current (DC) power via DC transmission lines and convert it into or from three-phase alternating current (AC) power, which is then routed to or from the first and second torque machines 60 and 62 for operation as motors or generators, respectively, via transmission lines. The converter module transmits electrical power to and from the first and second torque machines 60 and 62 through the power converters and their respective motor control modules in response to motor torque commands. Electrical current is transferred to and from the battery via the high-voltage electrical bus to charge and discharge the high-voltage battery.

[0021] Controller 5 is linked to various actuators and sensors in the powertrain system via a communication link 15, both signal-wise and functionally, to monitor and control the operation of the powertrain system. This includes synthesizing information and inputs and executing routines to control actuators and thus achieve control objectives related to fuel economy, emissions, performance, drivability, and the protection of components, including the high-voltage battery cells and the first and second torque motors 60 and 62. Controller 5 is a component of the vehicle's overall controller architecture and provides coordinated system control of the powertrain.The controller 5 can comprise a distributed control module system containing individual control modules, including a monitoring control module, a power unit control module, a transmission control module, a battery pack control module, and the power converter module. A user interface is preferably connected via signaling to a plurality of devices through which a vehicle operator controls and commands the operation of the powertrain system, including commanding an output torque request and selecting a transmission range. The devices preferably include an accelerator pedal, an operator brake pedal, a transmission range selector (PRNDL), and a vehicle speed control system.The transmission range selector may have a discrete number of operator-selectable positions, which specify the direction of the vehicle's intended movement and thus the preferred direction of rotation of the output element 92, either forward or reverse. It should be noted that a vehicle may still move in a direction other than the operator-specified direction of movement due to rollback caused by the vehicle's position, e.g., on a hill. The operator-selectable positions of the transmission range selector may correspond directly to individual transmission ranges described with reference to Table 1 or may correspond to subsets of transmission ranges described with reference to Table 1.The user interface can comprise a single device, as shown, or alternatively, it can comprise multiple user interface devices directly connected to individual control modules.

[0022] The aforementioned control modules communicate with other control modules, sensors, and actuators via the communication link 15, which enables structured communication between the various control modules. The communication protocol is application-specific. The communication link 15 and suitable protocols ensure robust message transmission and interfaces for multiple control modules between the aforementioned control modules and other control modules that provide functionality such as anti-lock braking, traction control, and vehicle stability. Multiple communication buses can be used to improve communication speed and provide a degree of signal redundancy and integrity; these may include direct connections and serial peripheral interface (SPI) buses.Communication between individual control modules can also be achieved using a wireless connection, e.g., a short-range wireless communication bus. Individual devices can also be directly connected.

[0023] Control module, module, control, controller, control unit, processor and similar terms mean any of or various combinations of one or more of an application-specific integrated circuit(s) (ASIC), an electronic circuit, a central processing unit (preferably a microprocessor), and associated memory and storage (read-only memory, programmable read-only memory, random access memory, hard disk memory, etc.).The controller comprises one or more software or firmware programs or routines, a combinational logic circuit, an input / output circuit and input / output devices, suitable signal conditioning and buffering circuitry, and other components to provide the described functionality. Software, firmware, programs, instructions, routines, code, algorithms, and similar terms mean any set of instructions executable by a controller, including calibrations and lookup tables. The control module has a set of control routines that are executed to provide the desired functions.Routines are executed, for example by a central processing unit, to monitor inputs from sensors and other networked control modules and to perform control and diagnostic routines to manage the operation of actuators. Routines can be executed at regular intervals, known as loop cycles, for example every 3, 125, 6, 25, 12.5, 25, and 100 milliseconds, during the continuous operation of the power unit and the vehicle. Alternatively, routines can be executed in response to the occurrence of an event.

[0024] The multi-mode powertrain is designed to operate in a plurality of powertrain states, encompassing a plurality of transmission ranges and engine states, to generate torque and transmit it to the final drive. The engine states include an ON state, an OFF state, and a fuel cut-off (FCO) state. When the engine is in the OFF state, it is not supplied with fuel, does not ignite, and does not rotate. When the engine is in the ON state, it is supplied with fuel, ignites, and rotates. When the engine is in the FCO state, it rotates but is not supplied with fuel and does not ignite.The ON state of the engine can further include an all-cylinder state (ALLE), in which all cylinders are fueled and fire, and a cylinder deactivation state (DEAC), in which some cylinders are fueled and fire, and the remaining cylinders are not fueled and do not fire. The transmission ranges include multiple ranges of neutral, fixed gear, electric vehicle (EV#), and electrically adjustable mode (EVT mode#), achieved by selectively activating clutches C1 52, C2 54, and C3 56. The neutral range includes an electric torque converter (ETC) range, during which electrical power can flow to or from the battery in relation to the output torque, engine speed, output speed, and speed of any of the torque motors, although with zero traction torque output from the torque motors.Other powertrain states, e.g., transition ranges, can be used. Table 1 shows the powertrain states, which include transmission ranges and engine states for operating the multi-mode powertrain. Table 1 Area Power machine condition C1 C2 C3 Neutral 1 / ETC ON (ALL / DEAC / FCO) / OFF EVT mode 1 ONE(ALL / DEAC / FCO) X EVT mode 2 ONE(ALL / DEAC / FCO) X Procession 1 ONE(ALL / DEAC / FCO) X X 2 Motor EV OUT OF X X Motor A EV OUT OF X Motor B EV OUT OF X

[0025] The drivetrain configuration allows two power-split operating modes when the power machine is engaged, comprising the input power-split mode, e.g., EVT1, and the combined power-split mode, e.g., EVT2. These configurations allow the second torque machine 62 to be disconnected from the transmission output element 92 without interrupting the power flow from the power machine 12 and the first torque machine 60.

[0026] When operating in fixed gear 1, the drivetrain system has a single degree of freedom (1-dF) with respect to rotational speed. Thus, there is a single independent speed node, and all other speed nodes are linearly dependent on it. For example, all speed nodes encompassing the input speed (Ni) are proportional to the output speed (No). Exemplary governing equations include the following. [To]=[A1A2A3]∗[TaTbTi] and [NaNbNi]=[B1B2B3]∗[No] where Ta represents a torque output of the first torque machine 60, Tb represents the torque output of the second torque machine 62, Ti represents the input torque at element 14, i.e., from the power machine 12, To represent the output torque at element 92, Na the rotational speed of the first torque machine is 60, Nb represents the rotational speed of the second torque machine 62, Ni represents the input speed at element 14, No, the output speed is represented at element 92, and A1, A2, A3, B1, B2 and B3 are application-specific scalar values ​​that are determined on the basis of the gear relationships.

[0027] When operating in either the EV or EVT ranges, the powertrain system has two degrees of freedom (2 dF) with respect to rotational speed, thus allowing for two independent speed nodes. For example, all speed nodes except the input and output speeds can be calculated as a linear combination of the input and output speeds. Exemplary governing equations include the following. [TaTb]=[A11A12A21A22]∗[TiTo] and [NaNb]=[B11B12B21B22]∗[NiNo] where A11, A12, A21, A22, B11, B12, B21 and B22 are application-specific scalar values ​​determined on the basis of the gear relations.

[0028] When operating in the Neutral 1 / ETC range, the drivetrain system has three degrees of freedom (3 dF) with respect to rotational speed, comprising the input speed, the output speed, and one additional speed. In this range, there is no flexibility to select motor torques such that the battery power is zero for any given torque of the power machine. When no clutches are engaged, the transmission is in the Neutral 1 / ETC range. In this transmission range, the second torque machine 62 is decoupled from the transmission, allowing its speed to be controlled independently. The motor torque output Ta of the first torque machine 60 is proportional to the output torque To, and its speed is a linear combination of the input and output speeds. Exemplary governing equations include the following. [TiTaTb]=[A1A2A3][To] and [No]=[B1B2B3]∗[NiNaNb] where A1, A2, A3, B1, B2 and B3 are application-specific scalar values ​​determined on the basis of gear relations.

[0029] Fig. Figure 2 illustrates a control scheme 200 that is applied to control the system with reference to Fig. The purpose is to control the drivetrain system described in Section 1 to disengage one or more of the torque machines (hereafter referred to as Motor X), thereby generating a zero-torque output from them. This includes controlling the drivetrain system while transitioning to the disabled state for Motor X. This includes the work in the Neutral 1 / ETC region, which is described with reference to Table 1 and Equations 5 and 6. Table 2 is given as a key, with the numbered blocks and their corresponding functions performed as follows. Table 2 BLOCK BLOCK CONTENTS 202 Commands to shut down engine X 204 Converge the minimum and maximum torque capacity limits of motor X over time. 206 Allow the power machine control to switch from inactive to active. 208 Allow the minimum and maximum torques of the power machine to converge into a single torque command to the power machine in response to the minimum and maximum torque capacity limits of motor X and an output torque request. 210 Control the operation of the powertrain system in the state with the engine off. 212 Control the power machine in a state of active response in response to output torque demand. 214 Commands to exit the state of the engine being shut down 216 Increase the minimum and maximum torque capacity limits of motor X over time; control the torque of motor X in response to the Output torque requirement 218 Increase the minimum and maximum torque values ​​of the power machine; control the torque of the power machine in response to the output torque requirement and the torque of motor X within the minimum and maximum torque values ​​of the power machine. 220 Commands change the state of the power machine to a state of inactive response.

[0030] Data relating to the execution of an embodiment of the control scheme 200 in an exemplary embodiment of the powertrain system are available with reference to Fig.Figure 3 shows that during continuous operation of the drivetrain, there may be a command to disengage motor X, thus producing zero traction torque (202). The command to disengage motor X may be part of a command to operate in the Neutral 1 / ETC range. The command to disengage motor X may include a command to reduce the torque output from the torque machine in response to a reduced torque output from the torque machine, such as may occur due to overheating in the torque machine or a fault in the control system for the torque machine. A command to reduce the torque output from the torque machine in response to a reduced torque output may result in a reduced, but not zero, torque output from the torque machine.

[0031] The minimum and maximum torque capacity limits of motor X are allowed to converge to zero or the reduced torque output over a short period (204), which allows the control of the power machine to be instructed to switch from an inactive state to an active state (206) and to allow the minimum and maximum torques of the power machine to converge into a single torque command to the power machine in response to the minimum and maximum torque capacity limits of motor X and the output torque request (208). The convergence of the minimum and maximum torques of the power machine is preferably accomplished by allowing the minimum and maximum torques of the power machine to increase or decrease into a single, common torque command to the power machine based on the limitations of the motor torque, i.e.,The timing of the commands is modified, allowing the operation of the power machine to control the input torque and thus the input speed. When the aforementioned commands are fully executed, the operation of the drivetrain system is controlled in the off-engine state, with the torque command to motor X set to zero or the reduced torque command (210). If the command to off-engine X includes a command to reduce the torque output from the torque machine in response to the reduced torque capacity of the torque machine, the minimum and maximum torque capacities of either of the torque machines converge to the reduced torque capacity of the torque machine, which includes a reduction to a torque output of zero.

[0032] Operation in the state with the engine off, with the torque command set to zero, or with the torque capacity of engine X reduced, includes allowing the engine to be controlled in an active response state in response to the output torque request. This includes controlling the engine in response to an instantaneous torque command to the engine that is smaller than a predicted torque command to the engine, and thus an advance of the ignition spark that differs from the advance of the MBT ignition spark when the engine is configured as a spark-ignition internal combustion engine.This involves controlling the engine in response to an instantaneous torque command to the engine that is smaller than a predicted torque command to the engine, and thus at a fuel injection time that differs from an optimal fuel injection time, if the engine is designed as a compression-ignition internal combustion engine. The fast engine actuators can be used to easily change the torque of the engine, thereby providing a fast-responding engine reserve to increase or decrease the torque output of the engine (212).The operation of the power unit involves controlling the slow and fast power unit actuators, allowing the power unit's torque to be easily increased by advancing the ignition timing towards the same advance as the MBT ignition timing, or easily decreased by advancing the ignition timing further away from the MBT ignition timing. In this way, the power unit employs torque control, adjusting the power unit's torque output in response to the output torque demand. The torque output from engine X is held at zero, resulting in zero traction torque being generated by engine X.When operated as described, the power machine is capable of rapidly increasing or decreasing its torque, utilizing the fast-acting power machine actuator(s) in response to the output torque demand, while taking into account other actuators for the operation of the power machine and the drivetrain. Depending on the operating conditions, the power machine control can switch between the active and inactive states multiple times during operation, including the state with the motor off.

[0033] Operation in the disabled motor state can subsequently be interrupted (214), which involves increasing the magnitudes of the minimum and maximum torque capacity limits of motor X over time, i.e., allowing them to rise, and controlling the torque of motor X in response to the output torque request accordingly (216). In response, the magnitudes of the minimum and maximum power machine torques increase, and the torque of the power machine is controlled in response to the output torque request, and the torque of motor X is controlled within the limits defined by the minimum and maximum torques of the power machine (218). When these transitions are complete, the power machine control can be commanded to switch from the active state to the inactive state (220), and the powertrain system is controlled in response to the output torque request.

[0034] Fig. Figure 3 graphically shows a plurality of time coincidence parameters associated with the transition to and control of a drivetrain system in a transmission state where one of the torque machines (motor X) is disengaged. For example, one of the torque machines is disengaged when the drivetrain system is operated in an electrically neutral state, e.g., when the drivetrain system, which is operating with reference to Fig.1 is described, in which state Neutral 1 / ETC operates. The parameters include the torque of motor X 320 for one of the torque machines, e.g., the second torque machine 62, including minimum and maximum torque capacities of motor X 322 and 324 respectively, and the torque command to motor X 326, and a torque correction request for speed control of motor X 330. The parameters include torques of power machine 340, which include minimum and maximum system torque limits of power machine 341 and 342 respectively, an instantaneous torque command to power machine 343, a predicted torque command to power machine 344, and an air torque of power machine 345. The instantaneous torque command to power machine 343 represents a current command to control the operation of the power machine and reflects the actual torque of the power machine throughout the entire operating period, which is described in Fig.Figure 3 illustrates this. The predicted torque command to the engine 344 represents a long command for controlling the operation of the engine and a maximum torque capacity of the engine when the engine is operated with the MBT ignition spark advanced. The predicted torque command to the engine 344 is achieved by commanding operating states for slow engine actuators, e.g., throttle / air mass control or fuel quantity control, in response to the torque command to the engine. The air torque of the engine 345 responds to the predicted torque command to the engine 344 and represents an estimated instantaneous maximum torque of the engine, i.e., the maximum torque of the engine at the current amount of air per cylinder at the current rate of fuel injection.The engine achieves a torque equivalent to the engine's air torque when the air / fuel ratio is stoichiometric and the ignition timing is set to a knock-limited MBT ignition time. The instantaneous torque command to engine 343 is a short torque command that uses fast engine actuators, such as ignition timing control or fuel injection timing control, and slow engine actuators to control the engine's torque output in response to the torque command. The instantaneous torque command to engine 343 responds to an engine-based output torque range defined by the minimum and maximum system torque limits of engine 341, 342.The torque limitations of the power machine respond to the minimum and maximum torque capacities of motors X 322 and 324, the output torque requirement, and other factors. The time coincidence parameters include a torque response type of power machine 350, which comprises an inactive response of power machine 352 and an active response of power machine 354. The aforementioned parameters are all plotted relative to time 310. The inactive response of power machine 352 includes commands to control the operation of the power machine in response to a torque request to the power machine, applying the predicted torque command to power machine 344 and the slow-action power machine actuators.The active response of a power machine 354 includes commands to control the operation of the power machine in response to a torque request to the power machine, applying the instantaneous torque command to the power machine 343 and both the fast power machine actuators and the slow power machine actuators.

[0035] Prior to time 301, the drivetrain system operates with traction torque contributions from the power machine and one of the torque machines, designated as motor X. At time 301, motor X is taken out of service, e.g., in response to a command to operate in an electrically neutral state, resulting in an immediate reduction of the minimum and maximum torque capacities of motors X 322 and 324, respectively. This reduction includes one of the minimum and maximum torque capacities of motors X 322 and 324 being set equal to the current torque command of motor 326.The command to operate in the electrically neutral state also causes the torque response type of power machine 350 to change from an inactive response state of power machine 352 to a responsiveness-limited response of power machine 354, with corresponding changes to the minimum and maximum system torque limits of power machines 341 and 342. This includes setting the maximum system torque limit of power machine 342 equal to the previous instantaneous torque command to power machine 343. The response state can frequently switch during periods of torque decline and increase, with the response type being set to the active state, i.e., the responsiveness-limited response of power machine 354, if necessary to achieve a rapid torque change by advancing the ignition timing.Operation in the limited response of the engine 354 with regard to the responsiveness is preferably minimized, since such operation can impair fuel economy.

[0036] During the period between times 301 and 302, the minimum and maximum system torque limits of power machine 341, 342 converge to the instantaneous torque command to power machine 343, and the minimum and maximum torque capacities of motor X 322, 324 converge to the torque command to motor X 326, which is reduced to zero torque at time 302. As shown, the torque of the power machine remains unchanged for a short period after time 301 and then decreases in response to the dynamic aspect of the torque correction requirement for speed control of motor X 330 and the motor torque command 326. While the minimum torque capacity of motor X 322 decreases towards zero, the torque requirement for speed control of motor X initially moves in the same direction, i.e.,It increases, meaning that initially no change in the torque of the power machine is required.

[0037] The predicted torque command to the engine 344 is controlled to provide a reserve torque by maintaining the air torque of the engine 345 at a level greater than the instantaneous torque command to the engine 343. Thus, the air torque to the engine 345 is controlled in response to the predicted torque command to the engine 344, and the instantaneous torque command to the engine 343 is achieved by advancing the ignition timing away from the point of the MBT spark to provide a torque reserve for the engine.

[0038] The torque command from motor X 326 is set to zero at time 302 and is held there during operation while motor X is in the off state, which ends at time 303. The torque correction request for speed control of motor X 330 varies at a much lower frequency when no additional motor torque capacity is available, i.e., when the torque command to motor X equals the torque limit. This low-frequency torque correction request for speed control is achieved via software that applies smaller gains to the torque correction for speed control when the power machine is the actuator performing the speed control, in order to compensate for the slower response of the power machine compared to the response of torque machines.The air torque of the power machine 345 is controlled in response to the predicted torque command to the power machine 344, and the instantaneous torque command to the power machine 343 is controlled in response to the minimum and maximum system constraints of the torque of the power machines 341, 342, which have converged.

[0039] During operation with the motor X in a disabled state, the minimum and maximum torque capacities of motor X 322 and 324 are kept at zero, and speed control is achieved by the instantaneous torque command to the power machine 343, whereby a speed control reserve is maintained by the predicted torque command to the power machine 344.

[0040] In response to a command to exit the off-engine state, the minimum and maximum torque capacities of engines X 322 and 324 are changed back to normal engine torque limits. This is shown beginning at time 303 and ending at time 304. Accordingly, the minimum and maximum system torque limits of power units 341 and 342 diverge. Operation in which engine X generates torque is achieved before the power unit commands transition from the responsiveness-limited response of power unit 354 with spark control to the inactive response of power unit 352, which operates in response to the air torque of power unit 345 with MBT spark control.

[0041] Control scheme 200 effectively smooths transitions in the response of the power machine during transitions to and from a disabled engine state. This is achieved by maintaining torque control of the power machine throughout the transitions, employing the power machine as the primary torque actuator to control the input speed during disabled engine operation, such as that occurring in the Neutral 1 / ETC range. This operation avoids the lack of input speed control associated with using torque machines under such operating conditions.

Claims

[1] Method (200) for operating a multi-mode powertrain system comprising an electromechanical two-mode transmission (10) with combined power splitting, comprising two planetary gear sets (20, 30) and three engageable clutches (C1 52, C2 54, C3 56), configured to transmit torque between a power machine (12), two torque machines (60, 62) and an output element (92) in one of a plurality of transmission ranges comprising a fixed gear range (Fixed Gear 1), three electric vehicle ranges (Motor 2 EV, Motor A EV, Motor B EV), two electrically variable transmission ranges (EVT Mode 1, EVT Mode 2) and a neutral range (Neutral 1 / ETC), wherein no clutches (C1 52, C2 54, C3 56) are engaged in the neutral range, wherein the method (200) in response to a fault associated with the operation of one (X) of the torque machines (60, 62) includes: in response to a command to disable one (X) of the torque machines (60, 62) (202), which includes a command to operate the transmission (10) in a neutral range (Neutral 1 / ETC) and a command to reduce the torque output of one (X) of the torque machines (60, 62) to a torque output of zero, converging the minimum and maximum torque capacities of one (X) of the torque machines (60, 62) to zero (204), and converging the minimum and maximum system torque limits of the power machine (12) to a single torque command to the power machine (12) in response to the minimum and maximum torque capacity limits of one (X) of the torque machines (60, 62) and an output torque request (208); and Controlling the torque output from the power machine (12), which includes applying a fast power machine actuator to control the power machine (12) in response to the output torque request, and holding the torque output from one (X) of the torque machines (60, 62) to zero (212). [2] Method (200) according to claim 1, wherein the control of the torque output from the engine (12), which includes the application of the fast engine actuator, comprises controlling the engine (12) with an advance of the ignition spark, which differs from the advance of the MBT ignition spark when the engine (12) is designed as an internal combustion engine (12) with spark ignition. [3] Method (200) according to claim 1, wherein controlling the torque output from the engine (12), which includes applying the fast engine actuator, includes controlling the engine (12) with a fuel injection time that differs from an optimal fuel injection time when the engine (12) is designed as an internal combustion engine with compression ignition. [4] Method (200) according to claim 1, wherein controlling the torque output from the power machine (12), which includes applying the fast power machine actuator, includes maintaining a speed control reserve by controlling a slow power machine actuator in response to a maximum torque capacity of the power machine (12) when the power machine (12) is operated with an advance adjustment of the MBT ignition spark.

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