Abstract: Control of operation of a hybrid powertrain is provided, wherein mechanical power flow to an output is controlled through selective actuation of torque-transfer clutches. Electric machines are coupled to an energy storage system for electric power flow. The electro-mechanical transmission is operated in a continuously variable operating range state, and, operation of the transmission is monitored. Absence of a mismatch between the commanded continuously variable operating range state and an actual operating state of the transmission is determined. Presence of a mismatch between the commanded operating range state and the actual operating state of the transmission may be determined. Operation of the powertrain is modified when a mismatch between the commanded operating range state and the actual operating state of the transmission is detected.

Abstract: A system for robust fault detection in an electrically variable, hydraulically controlled transmission includes independently monitoring hydraulic pressure within a hydraulic control circuit and electric machine rotation for detecting clutch state faults.

Abstract: A method for operating the powertrain includes monitoring operator inputs, monitoring a transmission output, and terminating an engine operating mode when a time-rate change in the transmission output exceeds a threshold absent a change in the monitored operator inputs.

Abstract: Monitoring operation of an electromechanical transmission having a hydraulic circuit with flow management valves and pressure control solenoids to actuate clutches and pressure monitoring devices to monitor the hydraulic circuit is provided. The transmission operates in fixed gear and continuously variable operating range states. The method comprises controlling position of one of the flow management valves to control operation in one of the operating range states. A fault is detected in the one of the flow management valves based upon outputs of the pressure monitoring devices during steady state operation in one of the continuously variable operating range states. A fault is detected in the one of the flow management valves based upon the output of one of the pressure monitoring devices during a transition in the flow management valve.

Abstract: A method and control system is presented to selectively actuate a plurality of clutches of a two-mode, compound-split, electro-mechanical transmission. The method comprises executing a shift operation from a first to a second operating mode and monitoring shift abort criteria. A revised shift operation is executed to control the transmission shift into a third operating mode effective to meet an operator request for output torque. The exemplary transmission has four fixed gear ratio modes and two continuously variable modes. The preferred shift abort criteria include: monitoring the operator request for output torque; identifying presence of a fault in an oncoming torques transfer device effective to facilitate operation in the second operating mode; monitoring an optimization routine for managing torque inputs from the plurality of torque-generative devices.

Abstract: A method and system to off-load motive torque from a clutch to execute a transmission shift is provided. The powertrain includes torque-generative devices operably connected to a two-mode, compound-split, hybrid electro-mechanical transmission. The method includes determining a commanded output torque, and a shift command. A first torque is transmitted by electrical motors, and is limited by their torque capacities. A supplemental motive torque is transmitted from an oncoming clutch. The supplemental motive torque is limited by a torque capacity of the oncoming clutch. Output torque of an internal combustion engine to the transmission is adjusted by an amount substantially equal to a difference between the commanded output torque and the first and the supplemental motive torques.

Abstract: There is provided a control system for electro-mechanical transmission that is selectively operative in a plurality of fixed gear modes and continuously variable modes comprising first and second electrical machines and four hydraulically-actuated clutches in fluid communication with a hydraulic circuit comprising first, second and third pressure control devices and first and second flow management valves. The control system is operative to selectively actuate the pressure control devices and the flow management valves based upon a demand for torque, presence of a fault, and temperatures of the electric machines.

Abstract: A method of testing an electric motor that is adapted to provide a desired electric motor output torque to a vehicle powertrain system comprising an engine and the electric motor which are operatively and selectively coupled to a transmission. The method includes the steps of determining an initial motor speed of the electric motor, determining a motor torque command as a function of the initial motor speed, applying the motor torque command to the electric motor to produce an output torque from the electric motor, measuring a resultant motor speed of the electric motor and establishing a motor status as a function of the resultant motor speed. The method may be implemented as a computer control and diagnostic algorithm.

Abstract: A method and an apparatus for controlling an electro-mechanical transmission selectively operative in a plurality of fixed gear modes and continuously variable modes is provided. The exemplary transmission comprises first and second electrical machines and a hydraulic circuit comprising a plurality of pressure control devices and flow management valves. The method comprises monitoring an operating temperature of the electrical machines. A cooling flow rate in the hydraulic circuit effective to reduce the operating temperature of the electrical machines is determined. Availability of active cooling for each of the electrical machines is determined. Hydraulic flow in the hydraulic circuit is selectively controlled.

Abstract: Synchronous shift control in a multi-mode, hybrid transmission utilizes motor torques to control clutch synchronizations and torque conditions thereacross for substantially torque disturbance free shifting from one mode to another.

Abstract: A control apparatus for a powertrain system comprising an engine and two electrical machines operably coupled to a two-mode compound-split electro-mechanical transmission is provided. It includes a system controller and two motor control processors. The system controller communicates with the motor control processors via two high speed communications buses and directly-linked serial peripheral interface buses. The motor control processors control flow of electrical power between the electrical machines and an electrical energy storage device. A second control device is operable to control the engine, preferably to control torque output. The internal combustion engine preferably has a crank position sensor which is signally connected to a dedicated input to the second control device and to a dedicated input to the system controller of the first control device.

Abstract: A method and control system is presented to selectively actuate a plurality of clutches of a two-mode, compound-split, electro-mechanical transmission. The method comprises executing a shift operation from a first to a second operating mode and monitoring shift abort criteria. A revised shift operation is executed to control the transmission shift into a third operating mode effective to meet an operator request for output torque. The exemplary transmission has four fixed gear ratio modes and two continuously variable modes. The preferred shift abort criteria include: monitoring the operator request for output torque; identifying presence of a fault in an oncoming torques transfer device effective to facilitate operation in the second operating mode; monitoring an optimization routine for managing torque inputs from the plurality of torque-generative devices.

Abstract: A shift control for an electrically variable transmission shifts between modes through a neutral mode wherein the output is decoupled from the transmission. Normally, shifts between modes are accomplished synchronously through a duration of fixed-ratio operation. Extreme driving conditions may invoke shifts through neutral mode. Ratio violations characterized by one mode being active in a preferred input/output ratio range for another mode are handled by a shift through neutral. Similarly, rapid acceleration and deceleration conditions likely to result in undesirable engine speeds if synchronous shifting is employed are handled by a shift through neutral.

Abstract: A control system is provided to effect a method to control torque output from a two-mode, compound-split, electro-mechanical transmission during gear-to-gear shifting event when an off-going torque-transfer device is disengaged. It includes a computer program which controls transmission operation. A predetermined preferred torque output from the transmission device is determined. Torque output from torque-generative devices device is controlled. Torque transmitted across a selectively actuated torque transfer device is controlled, and limited based upon available battery power. Actuation of the oncoming torque-transfer device is preferably based upon a temperature of the device during the shifting event. The temperature during the shifting event is determined based upon a rotational speed of an input shaft to the transmission and an elapsed time to shift.

Abstract: The invention comprises a method, an article, and a control system for controlling a powertrain having a main and an auxiliary hydraulic pump, with each pump operative to supply hydraulic fluid to a hydraulic circuit of the transmission. It includes determining a main pressure and a desired main pressure, and controlling the auxiliary hydraulic pump. Determining a main pressure in the hydraulic circuit comprises estimating hydraulic pressure. The auxiliary pump is controlled to an operating speed. Control of flow from the auxiliary and main pumps can comprise an exclusive ‘either-or’ flow, or a blended flow.

Abstract: A method and apparatus to control acceleration of a vehicle equipped with an electrically variable transmission and including a regenerative braking system, each are operably connected to a vehicle driveline. The method and apparatus include determining which one of a preselected shift selector position for the transmission is commanded, and determining operator demand for acceleration, using inputs from throttle pedal and brake pedal. Vehicle acceleration is measured, and magnitude of commanded torque transferred from the electrically variable transmission and the regenerative braking system to the vehicle driveline is controlled based upon the commanded preselected shift selector position, the operator demand for acceleration, and the measured vehicle acceleration.

Abstract: A method for providing an active engine stop of the engine of a hybrid electric vehicle. The method utilizes the electric machine to oppose and rapidly stop the rotation of the engine at a controlled rate. The method includes the calculation of an input speed reduction trajectory using the engine speed when the active engine stop request is made and a predetermined speed reduction interval. The speed reduction interval is less than a time from the active stop request to the shutoff command to the electric machine The method provides rapid deceleration of the engine, particularly through the powertrain resonance speed, reducing the amount of vibration energy dissipated through the powertrain and chassis. The method removes the electric machine torques from the engine prior to achieving zero engine speed in order to avoid imparting a negative engine speed or counter-rotation of the engine.

Abstract: A multi-mode hybrid transmission has speed control provided via an open loop model derived as a function of preselected transmission accelerations and controlled and uncontrolled transmission torques. Motor torques are selected as the controlled torques and other preselected transmission torques are selected as the uncontrolled torques. The control also employs a closed loop control effort responsive to at least one preselected transmission speed error.

Abstract: An electrically variable transmission has a pair of clutches and a first mode when the first clutch is applied and the second clutch released, a second mode when the second clutch is applied and the first clutch released, and a fixed-ratio mode when both clutches are applied. Upshifts and downshifts out of fixed-ratio are accomplished in accordance with a control based upon shift confidence factors determined in accordance with proportional and derivative input speed error quantities. Additional authority limits are placed upon the shift confidence factors in accordance with output speed derivative quantities. Additional override downshift control is provided in accordance with additional input speed condition determinations.

Abstract: A hybrid powertrain has a transmission including a motor and a sensor for sensing rotation of the transmission output member. Motor speed signals are available from the motor controller. Speed signals representative of output speed are calculated from both the speed sensor and the motor speed in conjunction with known speed relationships between the motor and the output. A variety of in-range and dropped signal diagnostics is performed for the sensors and are used in the development of a set of software switches for selecting which of the speed sources is used as the output speed.