A hybrid electric vehicle capable of starting an engine in the event of failure of a DC-DC converter and a method of controlling the hybrid electric vehicle are provided. The hybrid electric vehicle includes a driving motor, an engine, and a first relay that starts a starter. A second relay is disposed between a first power line, connected the starter and a first battery, and second power line, connects a DC-DC converter that converts the power of a second battery and an electric load. A controller selectively adjusts the states of the first relay and the second relay. Upon determining starting of the engine and detecting failure of the DC-DC converter, the controller maintains the on state of the second relay and turns on the first relay to perform cranking of the engine.

A hydraulic system is disclosed for assisting starting of a machine having an engine. The hydraulic system may include a work tool, a pump driven by the engine to pressurize fluid, and an actuator configured to receive pressurized fluid from the pump and move the work tool. The hydraulic system may also include an accumulator configured to selectively receive pressurized fluid from the pump and from the actuator, an electric starter configured to start the engine, and a motor selectively supplied with fluid from the accumulator to assist the electric starter in starting the engine.

According to some embodiments, a start-stop system for a vehicle is disclosed. The start-stop system includes a first energy storage device coupled to a starter motor. The start-stop system also includes a first DC-to-AC inverter coupled to the first energy storage device, a starter/alternator coupled to the first DC-to-AC inverter, and a second DC-to-AC inverter coupled to the starter/alternator. The start-stop system further includes a second energy storage device coupled to the second DC-to-AC inverter. The start-stop system finally includes a controller configured to control the two DC-to-AC inverters such that either the starter motor or starter/alternator starts the vehicle based on the state of charge of the second energy storage device.

A start-up method of a mild hybrid system determines whether start-up is attempted through an MHSG in accordance with a request for start-up from a driver, compares an engine rpm at the end of cranking with a reference rpm in start-up using the MHSG, determines whether an engine rpm immediately after start-up follows an idle target rpm when the engine rpm at the end of cranking exceeds the reference rpm, checks whether there is an error in a cam angle sensor when poor following in which the engine rpm immediately after start-up does not follow the idle target rpm is generated, forcibly changes an engine state into cranking when the cam angle sensor has an error, and executes an existing backup crank logic that decreases a target rpm of the MHSG and finds out a fuel injection time while performing test injection using a signal from an crank angle sensor.

A method and system for operating a vehicle that includes a plurality of engine starting devices and an internal combustion engine is described. In one example, the method selects one of a plurality of engine starting devices to start an engine based on durability metrics of each of the plurality of engine starting devices. In addition, engine starting device selection may be based on calibration parameters that are generated via a server that is external to the vehicle.

A starting control device for an internal combustion engine is provided with a hard cranking device and a soft cranking device that are respectively capable of and incapable of cranking the internal combustion engine to a target idle rotation speed. The starting control device includes: a starting mode determination unit determining whether to carry out starting in a non-combustion pressure mode whereby starting is carried out with the hard cranking device, or in a combustion pressure combination mode whereby starting is carried out through cranking with the soft cranking device while using a combustion pressure generated by supplying fuel to the internal combustion engine in combination; and an intake air amount control unit making an amount of intake air during cranking differ between a case where starting is carried out in the non-combustion pressure mode and a case where starting is carried out in the combustion pressure combination mode.

A control device according to the present invention performs an automatic stop control in which an injection of fuel from a fuel injection valve is stopped and a rotation of an engine is stopped when an automatic stop condition is satisfied. Furthermore, the control device controls an injection operation of fuel and an ignition operation to the fuel in consideration of compression when the fuel is actually ignited in an expansion stroke cylinder, when a re-start demand occurs after an initiation of the automatic stop control and the engine is to be re-started by an ignition start-up. Specifically, the control device predicts a crank angle at an actual ignition time point in a case where processing for performing the ignition start-up at the present time whenever a predetermined time period has passed. Then, the control device initiates the ignition start-up when the crank angle falls within a predetermined range in which a sufficient compression can be attained. Thereby, the engine is more certainly re-started by the ignition start-up.

A system and method for controlling engine starting in a hybrid vehicle having first and second electric machines include starting the engine in response to an engine start request using the first electric machine and releasing second electric machine reserved engine starting torque for use in propelling the vehicle. The first electric machine may be controlled to start the engine in response to the first engine start after key-on and when the vehicle speed is below a corresponding threshold, with the second electric machine used when vehicle speed is above the threshold. The first electric machine may be an integrated starter-generator.

A system and method for controlling engine starting in a hybrid vehicle having an engine, a first electric machine selectively coupled to the engine by a first clutch, a second electric machine coupled to the engine, a step-ratio transmission selectively coupled to the electric machine by a second clutch include starting the engine using either the first electric machine or the second electric machine based on engine stop position. The first electric machine may be a low voltage starter motor or integrated starter-generator. The system and method may use the first electric machine when the engine stop position is within a specified range of positions relative to a piston top dead center position associated with higher cranking torques.

Systems and methods for improving operation of a hybrid vehicle are presented. In one example, an engine may be started in one of two ways depending on operating conditions. In particular, the engine may be started via a lower power output electric machine or a higher power output electric machine.