A method of operating an accessory drive system for a motor vehicle, wherein the accessory drive system includes one or more accessory components, a motor generator of the motor vehicle, and a flexible drive element configured to transmit a torque load between the one or more accessory components and the motor generator, includes determining a maximum permissible flexible drive element torque threshold, detecting an increase in torque demand on the flexible drive element, determining when the torque demand on the flexible drive element will exceed the flexible drive element torque threshold, and reducing the torque demand of one or more of the accessory components so that the flexible drive element torque threshold is not exceeded.

A method for operating a vehicle that may be automatically stopped and started is described. In one example, the method includes starting an engine via expansion stroke combustion in response to a request to urgently start the engine. In addition, the method includes adjusting a position of a compression relief valve in response to a predicted urgency of an engine start.

Systems and methods for starting an internal combustion engine of a hybrid vehicle are presented. In one example, the internal combustion is started via closing a driveline disconnect clutch and limiting a torque output rate of an electric machine so that vehicle speed may increase continuously without decreasing during engine cranking and run-up periods.

A system for controlling a lock-up of engine clutch may include an engine and a motor; the engine clutch mounted between the engine and the motor and configured to selectively transmit power of the engine between the engine and the motor; a hybrid starter generator (HSG) connected to a crank pulley of the engine and driven to start the engine; and a controller connected to the HSG and configured to determine a virtual engine speed in an engine firing process and a torque reduction ratio of the HSG according to the virtual engine speed after an engine cranking process and determine a correction reduction ratio with respect to the torque reduction ratio of the HSG using a difference value between the virtual engine speed and an actual engine speed, and adjust an increase or a decrease of the torque reduction ratio of the HSG to synchronize an engine speed with a motor speed for the lock-up of the engine clutch.

A method for operating a vehicle that may be automatically stopped and started is described. In one example, the method includes supply electrical current to a starter motor independently from supplying electrical current to a starter solenoid. In addition, the method includes adjusting and amount of electrical current that is delivered to the starter motor in response to a level of urgency of an automatic engine start.

Systems and methods for operating a hybrid vehicle are described. In one example, a torque reserve for starting an engine via an electric machine is adjusted responsive to vehicle operating conditions. The torque reserve may set aside a portion of torque that an electric machine may produce for cranking and starting an engine.

An enhanced engine starter system controls an air turbine starter at the startup of operation of a turbine engine. The engine starter system includes an air turbine starter (ATS) that operates in accordance with more than one speed/torque curve during the startup procedure. A controller commands the starter control valve to provide a regulated pressure to the ATS in accordance with a first speed/torque curve to initiate the gas turbine engine startup without exceeding a maximum or design limiting torque. Overall duration of the startup procedure is reduced by the controller subsequently operating the ATS in accordance with a second speed/torque curve having a higher operational pressure once the ATS reaches a predetermined transition speed. The torque at the predetermined transition speed on the higher pressure second curve remains less than the design limiting torque, but provides a higher torque as compared to the first speed/torque curve to reduce the duration of the startup procedure.

Aspects of the present invention relate to a control system 12, method 400 and computer program 31 for controlling torque provided by a belt integrated starter generator 14 of a vehicle 10, the control system 12 comprising one or more electronic controllers 18, the one or more electronic controllers configured to: determine a change in torque to be provided by the belt integrated starter generator 14 according to a torque request 54; determine that the change in torque will cause the belt integrated starter generator 14 to enter a torque reversal region 51; and generate and output to the belt integrated starter generator 14 an altered torque request 56 within the torque reversal region 51, wherein the altered torque request 56 is generated and output to the belt integrated starter generator 14 when the torque request 54 would result in a reduction in the amount of torque provided by the belt integrated starter generator and when the torque request would result in an increase in the amount of torque provided by the belt integrated starter generator.

Systems and methods for operating various components of a hybrid driveline during starting of an internal combustion engine are described. In one example, output of an electric machine is not adjusted during engine starting when a speed of the electric machine exceeds a threshold speed so that torque reporting is accurate and to ensure combustion is reliable.

A method for starting an internal combustion engine (ICE) having a crankshaft and an electric turning machine (ETM) operatively connected to the crankshaft comprises energizing an absolute position sensor adapted for providing an indication of an angular position of a rotor of the ETM and applying a current to the ETM to generate a sufficient torque to rotate the crankshaft.