Method for controlling a multi-mode powertrain system

Abstract

Method for controlling a multi-mode powertrain system (100) comprising a transmission (10) configured to transmit torque between an internal combustion engine (12), torque machines (60, 62) and an output element (92), the method comprising: operating the multi-mode powertrain system (100) to execute an intake manifold pump-out mode (412) of the engine (12) (130), which includes closing a throttle valve of the engine (12) and controlling one of the torque machines (60, 62) to rotate the engine (12) and pump out the intake manifold;and aborting the intake manifold pump-out mode (412) of the power machine (12) and supplying the power machine (12) with fuel (210, 150, 155), wherein the aborting is based on the intake manifold pressure and system constraints (202, 204, 206), wherein the aborting of the intake manifold pump-out mode (412) of the power machine (12) based on the intake manifold pressure and system constraints (202, 204, 206) includes aborting if system constraints (206) are violated during the pump-out event, and wherein a violation of system constraints during the pump-out event (206) includes one resulting from exceeding an operator torque request, exceeding a battery power limit, exceeding a battery discharge limit, and exceeding a torque capacity of one of the torque machines (60, 62).

Description

This disclosure relates to control devices for dynamic systems associated with multi-mode powertrain systems employing multiple torque-generating devices. Powertrain systems can be designed to transmit torque from multiple torque-generating devices 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-generating devices 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-generating devices 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 independently of a torque input from the internal combustion engine. These torque machines can convert the vehicle's kinetic energy, transferred 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 ensures functional control of the hybrid powertrain, which includes controlling the transmission operating state and gear shifting, controlling the torque-generating devices, and regulating the electrical energy exchange between the electrical energy storage device and the electric machines to manage transmission outputs that include torque and speed. German patent application DE 10 2008 059 983 A1 discloses a method for controlling a multi-mode drivetrain system comprising a transmission configured to transmit torque between an internal combustion engine, a torque converter, and an output element. The method includes operating the multi-mode drivetrain system to execute an intake manifold pump-out mode of the engine, which involves closing a throttle valve of the engine and controlling the torque converter to rotate the engine and pump out the intake manifold. The method also includes terminating the intake manifold pump-out mode of the engine and supplying fuel to the engine, the termination being based on the intake manifold pressure and system constraints. The subsequently published German patent DE 10 2013 215 019 A1 discloses a method for operating a multi-mode drivetrain to achieve the starting of a catalytic converter. It also includes an engine auto-stop mode (FCO mode) for engine operation, in which the engine crankshaft rotates while the engine is not supplied with fuel and the throttle valve is closed. Upon termination of the FCO mode, the system switches from the engine auto-stop mode to an engine on state. From DE 10 2010 034 829 A1, a series hybrid drivetrain is known which includes an electric drive mode in which the drive is provided by an electric motor that pulls an internal combustion engine which, in this mode, is not supplied with fuel. To reduce the resistance generated by pumping losses in the internal combustion engine in this mode, the throttle valve is opened so that air can enter and exit the intake manifold unhindered. To return to an operating mode with internal combustion engine drive, the throttle valve is selectively closed, applying a specifically calculated increment of the intake air quantity. When a target intake quantity is reached, the internal combustion engine is ignited. German patent DE 10 2006 010 768 A1 discloses a method for reducing engine torque disturbances during the starting of an internal combustion engine having an intake manifold and multiple combustion chambers. The method includes emptying the intake manifold and, after emptying, starting the engine, which involves forcing the engine to rotate and supplying an air / fuel mixture to the combustion chambers for combustion. During the intake manifold emptying process, essentially all leakage paths to the intake manifold are closed, and the gases are pumped out of the intake manifold and into the exhaust pipe of the internal combustion engine using a secondary air injection reaction pump. The object of the invention is to provide a method for controlling a drive train system in which the inlet manifold pumping mode of the engine is terminated in an alternative manner. This problem is solved by a method having the features of claim 1 and a method having the features of claim 4. Advantageous embodiments are specified in the dependent claims. The invention is described below by way of example with reference to the drawings: Fig. 1 illustrates a vehicle with a multi-mode powertrain system comprising an internal combustion engine, a transmission, and a final drive, as disclosed; Fig. 2-1 illustrates a release process of a pump loss reduction (DPLR) mode during deceleration fuel cut-off (dFCO) for controlling a multi-mode powertrain system employing a power unit configured to operate in the DPLR mode, as disclosed; Fig. 2-2 illustrates an exit process of the DPLR mode associated with a release process of the DPLR mode, as disclosed; Fig. 2-3 illustrates a pump-out termination and fuel replenishment logic associated with an exit process of the DPLR mode, as disclosed; and Fig.Figures 4-1, 4-2 and 4-3 illustrate the operation of the multi-mode powertrain system, which performs an embodiment of an exit process of the DPLR mode in response to a torque request from the accelerator device, which includes a regular or moderate throttle command from the accelerator device (tip-in), a full throttle command from the accelerator device and a soft throttle command from the accelerator device, according to the disclosure. Now, with reference to the drawings, in which the illustrations serve only to demonstrate certain exemplary embodiments and not to limit them, Fig. 1 shows a non-limiting embodiment of a vehicle 8 having a multi-mode drivetrain system 100 configured to transmit traction torque to one or more wheels 99 for propulsion. The multi-mode drivetrain system 100 comprises an internal combustion engine (power engine) 12, a multi-mode transmission (transmission) 10, a high-voltage electrical system 80, a final drive 90, and a controller 5. The transmission 10 is mechanically coupled to torque generators comprising the power engine 12 and the first and second torque generators 60 and 62, respectively, and is configured to transmit torque between the power engine 12, the torque generators 60 and 62, and the final drive 90.As illustrated, the first and second torque machines 60 and 62 are electric motors / generators. The final drive 90 comprises a differential system coupled via an axle 96 to one or more of the wheels 99 and is characterized by a finite drive ratio that provides torque multiplication for the driven wheels. In one embodiment, the final drive 90 is configured in a rear-wheel drive arrangement. Alternatively, the drive train 90 can be configured to operate, without restriction, in a front-wheel drive arrangement, an all-wheel drive arrangement, a four-wheel drive arrangement, or any other arrangement. The high-voltage electrical system 80 comprises an electrical energy storage device, e.g., a high-voltage battery (battery) 85, which is electrically coupled to a geared power converter control module (TPIM) 82 via a high-voltage electrical bus 84, 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 85 can be any suitable high-voltage electrical energy storage device, e.g., a high-voltage battery, and preferably comprises a monitoring system that provides a measure of the electrical power supplied to the high-voltage electrical bus 84, comprising voltage and electrical current. The engine 12 can be any suitable internal combustion unit and preferably 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, and can be a spark-ignition or compression-ignition engine. The engine 12 preferably comprises an electronically controlled throttle device for metering the intake air flow and a manifold pressure (MAP) sensor for monitoring the manifold pressure, which is preferably measured with respect to an absolute pressure. The engine 12 comprises a crankshaft coupled to the input element 14 of the transmission 10. A speed sensor 11 monitors the crank angle and speed of the input element 14. Power delivered by the engine 12, i.e.,The speed and torque of the power unit 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 power unit 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 drive train in response to operating conditions.The controller 5 is designed to control actuators of the power unit 12 and thus control combustion parameters, including the control of the 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. Thus, the speed of the power unit can be controlled by controlling combustion parameters, including air flow torque and ignition-induced torque. The speed of the power unit can also be controlled by controlling the reaction torque at the input element 14 by controlling the engine torques of the first and second torque units 60 and 62, respectively. The exemplary transmission 10 is an electromechanical four-mode transmission 10 with combined power splitting, comprising three planetary gear sets 20, 30, and 40 and five engageable torque transmission devices, i.e., clutches C1 52, C2 54, C3 56, C4 58, and C5 50, although a person skilled in the art will recognize the applicability of the present disclosure to alternative transmissions. The transmission 10 is coupled to a first and second torque machine 60 and 62, respectively. The transmission 10 is configured to transmit torque between the power machine 12, the torque machines 60 and 62, and the output element 92 in response to an output torque request. In one embodiment, the first and second torque machines 60 and 62 are motors / generators that use electrical energy to generate and counteract torque.The planetary gear set 20 comprises a sun gear element 22, a ring gear element 26, and planet gears 24, which are coupled to a carrier element 25. The carrier element 25 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 35. The planet gears 34 are arranged in a meshing relationship with both the sun gear element 32 and the ring gear element 36. The carrier element 35 is coupled to the rotatable shaft element 16. The planetary gear set 40 comprises a sun gear element 42, a ring gear element 46, and planet gears 44, which are coupled to a carrier element 45. As shown, a first and second set of planet gears 44 are coupled to the carrier element 45.Thus, the planetary gear set 40 is a compound sun gear element-pinion gear-pinion gear-ring gear element gear set. The carrier element 45 is rotatably coupled between couplings C1 52 and C2 54. The sun gear element 42 is rotatably coupled to the rotatable shaft element 16. The ring gear element 46 is rotatably coupled to the output element 92. As used herein, couplings refer to torque transmission devices that can be selectively engaged in response to a control signal and can be any suitable devices, including, for example, single or compound plate couplings or packs, one-way couplings, and band couplings. A hydraulic circuit 72 is configured to control the engagement states of each of the couplings with hydraulic pressurized fluid supplied by an electrically driven hydraulic pump 70, which is functionally controlled by the controller 5. Couplings C2 54 and C4 58 are hydraulically engaged rotary friction couplings. Couplings C1 52, C3 56, and C5 50 are hydraulically controlled brake devices that can be fixed to a gearbox 55.In this embodiment, each of the clutches C1 52, C2 54, C3 56, and C4 58 is hydraulically engaged using hydraulic pressure fluid supplied by the hydraulic control circuit 72. The hydraulic circuit 72 is functionally controlled by the controller 5 to engage and disengage the aforementioned clutches, to supply hydraulic fluid for cooling and lubricating transmission components, and to supply hydraulic fluid for cooling the first and second torque motors 60 and 62. Hydraulic pressure in the hydraulic circuit 72 can be determined by measurement using a pressure sensor(s), by estimation using onboard routines, or by other methods. The first and second torque machines 60 and 62 are three-phase AC motor / generator machines, each comprising a stator, a rotor, and a position sensor, e.g., a resolver. The motor stator for each of the torque machines 60 and 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 hollow shaft 18 coupled to the first planetary gear set 20. The rotor for the second torque machine 62 is fixed to a hollow shaft hub 19, which is mechanically attached to the second planetary gear set 30.Each resolver is connected to the TPIM 82 both signal-wise and functionally, and each detects and monitors the rotational position of the resolver rotor relative to the resolver stator, thereby monitoring the rotational position of the first and second torque machines 60 and 62, respectively. Additionally, the signals output by the resolvers can be used to determine the rotational speeds of the first and second torque machines 60 and 62. 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 in this embodiment is transmitted to one or more of the wheels 99 via a differential gear or other suitable device. The output power at the output element 92 is characterized by an output speed and an output torque. A transmission output speed sensor 93 monitors the speed and direction of rotation of the output element 92. Each of the wheels 99 is preferably equipped with a sensor configured to monitor the wheel speed and thus determine the vehicle speed and absolute and relative wheel speeds for brake control, traction control, and vehicle acceleration management. Each wheel 99 is preferably equipped with a controllable wheel brake 98, which may have any suitable configuration, e.g.An embodiment of a disc brake. Each wheel brake 98 exerts a mechanical braking torque 97 to resist the rotation of the corresponding wheel 99, wherein a brake controller 9 controls the mechanical braking torque 97 in response to a braking force 113 commanded by the operator. The mechanical braking torque 97 can directly correspond to the braking force 113 commanded by the operator. Alternatively, the mechanical braking torque 97 can respond to the braking force 113 commanded by the operator, taking into account an electrical braking torque induced in the drive train 90 by the output element 92 due to an electrically induced reaction torque from one or both of the first and second torque machines 60, 62. The electrically induced reaction torque from one or both of the first and second torque machines 60, 62 can be assigned to a regenerative braking system. 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 battery 85. The battery 85 is coupled to the TPIM 82 via the high-voltage DC electrical bus 84, which preferably includes a contactor that allows or prohibits the flow of electrical current between the battery 85 and the TPIM 82. The TPIM 82 preferably comprises a pair of power converters and respective motor control modules configured to receive torque commands and control the converter states accordingly, thus providing motor drive or recuperation functionality for electrical current to comply with the motor torque commands.The power converters comprise complementary three-phase power electronics, and each includes a plurality of insulated-gate bipolar transistors (IGBTs) for converting DC power from battery 85 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 comprises a pair of IGBTs. The states of the IGBTs are controlled to provide mechanical motor drive power generation or electrical energy recuperation functionality.The three-phase converters receive or supply DC electrical power via DC transmission conductors 27 and convert it into or from three-phase AC power, which is routed to or from the first and second torque machines 60 and 62 for operation as motors or generators, respectively, via transmission conductors. The TPIM 82 transmits electrical power to and from the first and second torque machines 60 and 62 through the power converters and respective motor control modules in response to the motor torque commands. Electrical current is transmitted to and from the battery 85 via the high-voltage electrical bus 84 to charge and discharge the battery 85. The battery 85 is characterized by a state of charge (SOC), and the drive system operation involves maintaining the battery 85's SOC within a predetermined range. The 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 battery 85 and the first and second torque motors 60 and 62. The controller 5 is a component of the vehicle's overall control 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 TPIM 82. The controller 5 is signal-connected to the brake controller 9 via communication link 15 to coordinate the operational control of the vehicle braking, as described herein. A user interface 13 is preferably signal-connected 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.A vehicle operator directs and commands the operation of the powertrain system, including an operator-commanded acceleration torque 112, which is entered by an accelerator pedal; an operator-commanded braking force 113, which is entered by a brake pedal; an operator-commanded transmission range 114, which is entered by a range selector (PRNDL); and an operator-commanded vehicle speed 116, which is entered by a cruise control system. The acceleration torque 112 commanded by an operator, which is entered by the accelerator pedal, can range from a 0% level, which indicates no operator input into the accelerator pedal, to a 100% level, which indicates maximum operator input into the accelerator pedal, which is an operator request for maximum output torque from the powertrain system, often referred to as a full-throttle (WOT) maneuver.The braking force 113 commanded by the operator can range from a 0% level, indicating no operator input to the brake pedal, to a 100% level, indicating operator input to the brake pedal commanding a braking torque up to the maximum achievable braking torque. The transmission range selection device can provide a discrete number of operator-selectable transmission ranges, indicating an operator-intended direction of travel for the vehicle, either forward or reverse, thereby specifying a preferred direction of rotation of the output element 92. It should be noted that the vehicle may still move in a direction other than the specified direction of travel intended by the operator due to rollback caused by the vehicle's position, e.g., on a hill.The operator-selectable positions of the gear range selector can correspond directly to individual gear ranges described with reference to Table 1, or they can correspond to subsets of the gear ranges described with reference to Table 1. The user interface 13 can comprise a single device, as shown, or alternatively, it can comprise multiple user interface devices directly connected to individual control modules. 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 specific 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, including 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. Control module, module, control, controller, control unit, processor and similar terms mean any or various combinations of one or more application-specific integrated circuits (ASICs), electronic circuits, central processing unit(s) (preferably a microprocessor) and associated memory and storage (read-only, programmable read-only, random access, disk, etc.) that executes one or more software or firmware programs or routines, combinational logic circuit(s), input / output circuit(s) and facilities, suitable signal conditioning and buffering circuitry and other components to provide the described functionality.Software, firmware, programs, instructions, routines, code, algorithms, and similar terms refer to any set of instructions, 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 sensing devices and other networked control modules, and to execute control and diagnostic routines to manage the operation of actuators. Routines can be executed at regular intervals, called loop cycles, for example, every 3, 125, 6, 25, 12.5, 25, and 100 milliseconds, during the continuous operation of the power unit and vehicle. Alternatively, routines can be executed in response to the occurrence of an event. The multi-mode powertrain 100 is designed to operate in a plurality of powertrain states, encompassing a plurality of transmission ranges and power machine states, to generate torque and transmit it to the final drive 90. The transmission ranges include a plurality of ranges from neutral (Neutral), fixed gear (Gear #), variable mode (EVT Mode #), electric vehicle (EV#), and transition (EV Transition Range# and Pseudo-Gear#), achieved by selectively activating clutches C1 50, C2 52, C3 54, C4 56, and C5 58. The pseudo-gear ranges are variable-mode transmission ranges in which the amount of torque output by the transmission to the final drive correlates with the amount of input torque from the power machine, taking into account torque losses associated with the torque-consuming components at the input element 14.The pseudo-gear range(s) can be used as intermediate gear ranges during switching between EVT mode ranges and can also be used as stationary gear operating states. The engine states include an ON state and an OFF state. The engine is considered to be in the ON state when it is rotating. The ON state of the engine can include an all-cylinder state (ALLE), where all cylinders are fueled and fire to produce torque, and a cylinder deactivation state (DEAC), where some cylinders are fueled and fire to produce torque, and the remaining cylinders are not fueled, do not fire, and do not produce torque. The ON state of the engine further includes a fuel cut-off or overrun cut-off (FCO) state, where the engine is rotating and all cylinders are not fueled and do not fire, thus producing no torque. When the engine is in the OFF state, it is not rotating.In one embodiment, operation with the power machine in the OFF state can be achieved by preventing rotation of the input element on the gearbox using a clutch or similar device. For example, the drive train system 100 shown with reference to Fig. 1 can operate with the power machine 12 in the OFF state, i.e., not rotating, by engaging clutch C5 50 to establish rotation of the input element 14 on the gearbox 55, controlling the speeds of the first and second torque machines 60, 62 to achieve an output speed and output torque that respond to the output torque requirement.Alternatively or additionally, operation with the power unit in the OFF state can be achieved by controlling the speeds of the torque units to achieve an input speed of zero and an output speed and torque that respond to the output torque demand. The output torque demand includes a request for positive output torque, resulting in vehicle acceleration and / or continuous driving. When the engine operates in the FCO state, it rotates but is not supplied with fuel and does not ignite. The engine can operate in response to an operator command for vehicle deceleration, such as when an operator lifts their foot off the accelerator pedal and allows the vehicle to coast, which is known as a deceleration-fuel cutoff state (dFCO). The engine can also be commanded to operate in the FCO state under normal operating conditions without deceleration. When operating in the dFCO state, the engine continues to rotate, drawing in and compressing air in the cylinders, a process known as engine pumping. Engine pumping is associated with negative torque, known as pumping loss, which can be used for vehicle braking under certain conditions but is otherwise undesirable.Pumping loss can be reduced or minimized under certain circumstances by adjusting the intake manifold pressure. This involves increasing the intake manifold pressure towards ambient pressure by opening the throttle valve and controlling other engine airflow actuators, such as cam phasers. A dFCO pumping loss reduction (DPLR) mode can be engaged or disabled under specific circumstances in response to an output torque request based on engine speed and operating conditions of the torque motors and battery. For example, the DPLR mode can be engaged in response to an output torque request involving an operator fully releasing their foot from the accelerator pedal while the vehicle is moving, if the engine speed is greater than a predetermined engine speed and the battery state of charge (SOC) is greater than a predetermined SOC.In contrast, DPLR mode can be locked in response to an output torque request, which includes an operator fully releasing their foot from the accelerator pedal while the vehicle is moving, if the engine speed is less than a preset engine speed, or if the battery state of charge (SOC) is greater than or less than a preset SOC. Other operating conditions for DPLR are related to the engine's ability to meet a commanded torque request, including, but not limited to, battery temperature (which includes temperatures below a minimum threshold or higher than a maximum threshold) and engine temperature (which includes temperatures above a maximum threshold). The powertrain control scheme involves, upon entering DPLR mode, the engine eventually being supplied with fuel and ignited to produce torque for vehicle propulsion and electrical power generation, typically in response to operator input into the accelerator pedal. A transition to engine operation in a torque-generating mode may involve closing the throttle valve, controlling other engine airflow actuators, such as cam phasers, and actuating one of the torque motors to rotate the engine, thereby pumping out intake manifold pressure before or in conjunction with fuel injection to effect such a transition. Fig. 2-1 schematically shows a DPLR mode release process 130 for controlling a multi-mode powertrain system employing a power machine configured to operate in DPLR mode, e.g., the multi-mode powertrain system 100 described with reference to Fig. 1. The DPLR mode release process 130 is used to determine whether to release operation in DPLR mode in a manner that balances battery power, battery discharge, and drivability issues related to powertrain responsiveness with an output torque demand and final drive feel. Table 1 is provided as a key to Fig. 2-1, with the numbered blocks and their corresponding functions as follows. Table 1 132 Monitoring of operator torque commands 134Requirement dFCO? 136DPLR available? 138Requirement for DPLR mode? 140 Execute dFCO without DPLR 142 Execute DPLR mode The release process 130 of the DPLR mode is executed as follows. During the continuous operation of the multi-mode powertrain system, operator torque commands (132) are monitored, preferably including operator-commanded acceleration torque, preferably applied by an accelerator pedal, and operator-commanded braking torque, preferably applied by a brake pedal. Other monitored parameters include the target power machine state, which has been determined based on cost optimization. The operator torque commands, which preferably include the operator-commanded acceleration torque input from the accelerator pedal, are evaluated to determine whether operation in dFCO mode is requested and / or remains in that mode (134). dFCO mode may be requested in response to various conditions (134)(1), including when the operator-commanded acceleration torque input from the accelerator pedal indicates that the vehicle operator has removed their foot from the accelerator pedal, low operator input to the accelerator pedal coupled with a high state of charge (SOC), and other conditions. Operation in DPLR mode may be blocked if DPLR mode operation is unavailable (136)(0). Under such circumstances, operation in dFCO mode may continue, but DPLR mode operation is blocked (140).If an operation is available in DPLR mode (136)(1), the system determines whether an operation in DPLR mode can be requested (138). Operation in DPLR mode cannot be requested (138)(0) if conditions are unfavorable. Possible unfavorable conditions include, but are not limited to, an anticipated imminent refueling event of the engine, an aggressive braking maneuver, low engine torque capabilities, low battery charging capabilities, and low battery discharging capabilities. If operation in DPLR mode is requested (138)(1), the powertrain system will operate in DPLR mode, which includes increasing the intake manifold pressure towards ambient pressure by opening the throttle valve and controlling other engine airflow actuators, such as cam phasers, to minimize pumping losses (142). Fig. 2-2 schematically shows an exit process 150 of the DPLR mode, which is executed when operation in the dFCO mode is rejected or interrupted (134)(0), and is primarily focused on exiting the DPLR mode following the release of operation in the DPLR mode. The exit process 150 of the DPLR mode is applied to determine how to exit operation in the DPLR mode. This includes ensuring that the intake manifold is sufficiently pumped out before refueling. Table 2 is given as a key to Fig. 2-2, with the numbered blocks and their corresponding functions performed as follows. Table 2 Table 2 134 Evaluate the dFCO requirement 150 DPLR mode exit process 152 Assess whether a dFCO leak (fuel refill event) is requested 154 Assess the need to pump out the intake manifold 155 Refuel internal combustion engine 156Stay in dFCO, perform intake manifold pump-out When fuel supply to the engine is requested (134)(0), with the system operating in dFCO mode (152)(1), the need to pump out the intake manifold is assessed (154), such operation being described with reference to Fig. 2-3. The pump-out mode may be initiated following operation in DPLR mode (154)(1) and is maintained (156) until the pump-out mode is aborted (154)(0). When the intake manifold has been sufficiently pumped out or has been aborted for other reasons, refueling of the engine is performed (155). Performing the pump-out mode includes maintaining operation in dFCO mode (156). Figure 2-3 schematically shows the abort logic 200 of the pump-out mode, which operates to balance the operator-commanded acceleration torque, battery power, battery discharge, and motor capabilities with drivability considerations related to the drivetrain's responsiveness to an output torque request and final drive feel. Table 3 is provided as a key to Figure 2-3, with the numbered blocks and their corresponding functions as follows. Table 3 202Is the airflow torque too high considering the torque requirements of the acceleration device? 204Is the airflow rate and torque too high considering the torque target? 206 Evaluate system limitations: Can system limitations be met during pumping? 210 Canceling the pumping mode and refilling with fuel 212 Perform pumping out the intake manifold The need to pump out the intake manifold is assessed by regularly and periodically monitoring and evaluating operating parameters, including airflow torque (202, 204), acceleration device torque request (202), target torque (204), and system constraints, which include operator-commanded acceleration torque, battery power limits, battery discharge limits, and motor capabilities (206). The acceleration device torque request corresponds to the operator-commanded acceleration torque 112, which is input by an accelerator pedal as described with reference to Fig. 1. The target torque is a torque with a system-generated amount to drive the power machine to satisfy the driver's torque request and system power requirements, such as generating electrical current, by one of the torque machines. The existing airflow torque is compared to a torque requirement of the accelerator device (202), and if it is deemed too high (202)(1), the system limitations are evaluated (206). Otherwise (202)(0), the existing airflow torque is compared to the target torque (204), and if it is deemed too high (204)(1), the system limitations are evaluated (206). Otherwise (204)(0), the pump-out event is aborted and refueling is initiated (210). Evaluating the system limitations (206) involves evaluating the torque requirement of the accelerator device, the battery power limits, the battery discharge limits, and the engine capabilities to determine whether any associated limitations can be met while the manifold is being pumped out (206)(1) or violated (206)(0).If the system constraints can be met during the pump-out process, the intake manifold is pumped out (212). Aborting the pump-out event and initiating refueling (210) results in the engine operating in a torque-generating state. Remaining in pump-out mode could be extended for drivability reasons, but can be aborted for fuel economy considerations, including battery state-of-charge issues. Executing the intake manifold pump-out process (212) involves reducing the intake manifold pressure by closing the throttle valve and controlling other airflow actuators of the engine, such as cam phasers, while the engine is rotating, to decrease the intake manifold pressure in response to the output torque demand. This may include commanding one of the torque motors to rotate the engine to effect the engine pump-out process. The system prepares for refueling by executing the engine pump-out process (212). Using the torque motors to pump out the intake manifold discharges the battery and is preferably minimized. The evaluation of drivability considerations includes monitoring the acceleration device's torque demand, the engine's airflow torque, and an optimal or target engine torque. The engine's airflow torque represents the amount of torque the engine can produce when fueled and controlled by an ignition timing at an MBT ignition setting under actual airflow conditions. The target engine torque is a measure of a preferred amount of engine torque produced in response to the output torque demand, based on a balance of engine torque, torque outputs from the torque motors, and battery power. Delaying the fuel supply to the engine until the intake manifold pumping process is complete and the engine's airflow torque is sufficiently low ensures a smooth transition to operating the powertrain system with the engine fully fueled and firing. Under conditions where the target engine torque is high, eliminating the delay results in a rapid torque response, provided the engine's airflow torque is high. Furthermore, this allows for a relatively slow refueling in response to a low torque demand from the accelerator.The assessment of system limitations considers whether battery discharge limits and engine limits can be met under current pump-out conditions, or whether immediate refueling is necessary to meet these limits with minimal consideration for drivability problems, or to smoothly exit operation in DPLR mode. Figures 4-1, 4-2, and 4-3 graphically depict the operation of the multi-mode powertrain system, which includes a power unit performing an embodiment of the DPLR mode exit process and the pump-out / stop and fuel recirculation logic described herein in response to different torque requests 406 from the accelerator device. These requests include moderate or nominally regular throttle input to the accelerator device, wide open throttle (WOT), and soft throttle input. The data shown include various amounts of torque on the vertical axis 402, each plotted against time on the horizontal axis 404. Fig. 4-1 graphically illustrates the operation of the DPLR mode exit process and the pump-out termination and fuel replenishment logic in response to a torque request 406 from the accelerator device, which includes a regular or moderate throttle input into the accelerator device. Monitored parameters include the airflow torque 410 of the engine, an engine torque associated with exiting the pump-out mode 412, a predicted engine torque 414 for controlling the airflow torque, and an instantaneous engine torque 416 for controlling the actual torque.At time 420, regular or moderate acceleration occurs in the accelerator, triggering a steep decrease in the instantaneous torque demand of the engine 416, thereby initiating the intake manifold pumping operation, and an increase in the engine torque associated with exiting the pumping mode 412. The engine torque demand, which is used to control the engine's operation and is specified by the predicted engine torque 414 and the engine torque 416, is delayed to allow the intake manifold pumping operation to proceed.At time 424, the airflow torque 410 of the engine matches the engine torque associated with exiting the pump-out mode 412, and the predicted engine torque 414 increases, thereby commanding the initiation of fuel supply to the engine, as indicated by element 418 switching from state 0 to state 1. The drop in the engine's airflow torque 410, caused by the intake manifold pump-out process, has a delayed response. Fig. 4-2 graphically illustrates the operation of the DPLR mode exit process and the pump-out termination and refueling logic in response to a torque request 406 from the accelerator device, which includes a wide-open throttle (WOT). At time 420, the accelerator device applies a wide-open throttle (WOT), triggering a momentary steep increase in the engine torque. This increase is associated with exiting the pump-out mode 412 at time 422, to a value exceeding the engine's airflow torque 410. Therefore, at time 422, the engine is refueled, as indicated by the element 418 switching from state 0 to state 1, thus without activating the pump-out mode prior to refueling. The delay between times 420 and 422 is solely due to signal processing.The resulting airflow torque of 410 from the power unit has a rapid response. Fig. 4-3 graphically illustrates the operation of the DPLR mode exit process and the pump-out termination and fuel replenishment logic in response to a torque request 406 from the accelerator device, which includes a gentle throttle input into the accelerator device. At time 420, a gentle throttle input into the accelerator device occurs, triggering a steep decrease in the instantaneous torque request 416 from the engine and a moderate increase in the engine torque associated with exiting the pump-out mode 412. The airflow torque 410 is adjusted after an extended period, indicated at time 426, thereby commanding the initiation of fuel supply to the engine, as indicated by element 418 switching from state 0 to state 1. Operation as shown in Fig.As shown in 3-4, in response to a torque request 406 of the accelerator device, which includes a gentle application of throttle to the accelerator device, the execution can be excluded in the manner shown if the battery charge level is low. Fig. 3 graphically illustrates the operation of a multi-mode powertrain system, as described, for example, with reference to Fig. 1, in which a release process of a pump loss reduction (DPLR) mode during deceleration overrun is executed in response to a dFCO request, a DPLR mode request, and a DPLR mode exit request. Monitored parameters include a dFCO request 302, fuel injection device operation 304, engine instantaneous torque request 306, engine air flow torque (Te air) 308, and a pump-out exit torque 310, all plotted against time on the horizontal axis. During the continuous operation of the multi-mode powertrain system, a dFCO request 302 is initiated, as shown at time 320, immediately followed by torque reduction by ignition timing retardation and subsequent deactivation of the operation 304 of the fuel injection device, as shown at time 322. At time 324, the instantaneous torque 306 of the engine requests the DPLR mode, which is activated at time 326, as indicated by an increase in the intake manifold pressure and the airflow torque 308 of the engine. At time 328, there is a request to exit dFCO. Because the DPLR mode has been activated, the execution of the pump-out mode is necessary, which is indicated by the drop in the instantaneous torque request 306 of the engine from the DPLR level to its minimum torque value. The engine initiates the pump-out of the intake manifold by closing the throttle valve, with a corresponding decrease in the airflow torque 308 of the engine. At time 330, the decreasing airflow torque 308 of the engine meets the pump-out torque 310, and consequently, the refueling of the engine is initiated, indicated by the deactivation of the dFCO request 302 with a corresponding torque request 306 from the engine. As a result, fuel injectors 304 are activated, and at time 332, all injectors have been refueled. In this way, the multi-mode powertrain system can activate and deactivate operation in the dFCO state and in the DPLR mode of the dFCO state.

Claims

Method for controlling a multi-mode powertrain system (100) comprising a transmission (10) configured to transmit torque between an internal combustion engine (12), torque machines (60, 62) and an output element (92), the method comprising: operating the multi-mode powertrain system (100) to execute an intake manifold pump-out mode (412) of the engine (12) (130), which includes closing a throttle valve of the engine (12) and controlling one of the torque machines (60, 62) to rotate the engine (12) and pump out the intake manifold;and aborting the intake manifold pump-out mode (412) of the power machine (12) and supplying the power machine (12) with fuel (210, 150, 155), wherein the aborting is based on the intake manifold pressure and system constraints (202, 204, 206), wherein the aborting of the intake manifold pump-out mode (412) of the power machine (12) based on the intake manifold pressure and system constraints (202, 204, 206) includes aborting if system constraints (206) are violated during the pump-out event, and wherein a violation of system constraints during the pump-out event (206) includes one resulting from exceeding an operator torque request, exceeding a battery power limit, exceeding a battery discharge limit, and exceeding a torque capacity of one of the torque machines (60, 62). Method according to claim 1, wherein the termination of the inlet manifold pumping mode (412) (140) of the power machine (12) based on the inlet manifold pressure and system constraints (210, 150) comprises a termination when an air flow torque (410) of the power machine (12) associated with the inlet manifold pressure reaches a torque demand of the accelerator device (202, 204). Method according to claim 1, wherein supplying the engine (12) with fuel (155) comprises supplying the engine (12) with fuel when a torque of the engine (12) associated with the inlet manifold pressure reaches a target torque of the engine (12). Method for controlling a multi-mode powertrain system (100) comprising a transmission (10) configured to transmit torque between an internal combustion engine (12), torque machines (60, 62) and an output element (92), the method comprising: in response to a command to interrupt operation of the multi-mode powertrain system (100) in a pump loss reduction (DPLR) mode (150) associated with a deceleration fuel cut-off (dFCO) mode: performing an intake manifold pump-out (130) that coincides with the operation of the engine (12) in the dFCO mode, which comprises closing a throttle valve of the engine (12) and controlling one of the torque machines (60, 62) to rotate the engine (12) and pump out the intake manifold; and re-pressurizing the engine (12) with fuel (155) when the inlet manifold pressure has been sufficiently pumped out. The method of claim 4, wherein re-pressurizing the engine (12) with fuel when the inlet manifold is sufficiently pumped out, comprises re-pressurizing the engine (12) with fuel (155) when a torque of the engine (12) associated with the inlet manifold pressure reaches a value associated with a torque request of an acceleration device. Method according to claim 5, wherein the torque requirement of the acceleration device is determined on the basis of an operator input into an accelerator pedal.

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