Systems and methods for operating exhaust valves of an internal combustion engine with poppet exhaust valves are described. The systems and methods provide for locking exhaust valves in a closed state when the exhaust valves are in mechanical communication with a base circle of a camshaft lobe. Locking the exhaust valves in a closed state may reduce the possibility of exhaust pressures opening the exhaust valves at times they may not be desired to be open.

An internal combustion engine includes an exhaust valve, a plurality of cams Ca, Cb, and Cc used to drive the exhaust valve, a cam-switching variable valve mechanism that selects a use cam used to drive the exhaust valve out of the plurality of cams Ca, Cb, and Cc, and an electronic control unit that determines whether switching abnormality of the use cam in the variable valve mechanism is present on the basis of a locus M in a predetermined period K which is a period in which the exhaust valve is opened. The locus M is a locus of an in-cylinder pressure changing rate dPc/dθ and is specifically a locus indicating a variation of the in-cylinder pressure changing rate dPc/dθ depending on a crank angle θ.

A novel latch seat for a switching rocker arm assembly used in variable valve actuation (VVA) systems for internal combustion engines. The seat is formed interactively in the assembled switching rocker arm using a novel fixture and press. The press interactively creates a curved dimple of the correct curvature, position and depth while measuring several lash dimensions. Since the latch seat is formed on the assembled rocker arm assembly, the latch seat depth is designed to account for the inaccuracies in the rocker arm assembly parts which create lash. Therefore all of the parts may be made with less precision since the latch seat is sized to compensate for the inaccuracies of all of the parts. The rocker arm assembly parts now may be manufactured to less stringent standards, but result in a rocker arm assembly with same accuracy of rocker arm assemblies manufactured to previous standards.

A diagnostic system for a vehicle includes a difference module, a Fourier module, and a fault module. The difference module determines pressure differences for a camshaft revolution based on differences between: first pressures within first chambers of a camshaft phaser measured during the camshaft revolution, wherein the first pressures within the first chamber control advancement of the camshaft relative to a crankshaft of an engine; and second pressures within second chambers of the camshaft phaser measured during the camshaft revolution, wherein the second pressures within the second chamber control retardation of the camshaft relative to the crankshaft of the engine. The Fourier module performs a Fourier Transform (FT) based on the pressure differences to produce FT data. The fault module, based on the FT data, selectively indicates that a fault is present in a variable valve lift mechanism that is actuated by the camshaft.

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 controller for controlling an internal combustion engine includes a valve timing adjuster, a variable valve lift mechanism and a processor. The processor controls a duty cycle of a drive signal in a selected one of control modes, thereby changing a relative rotational phase of a camshaft relative to an engine output shaft. The control modes include a specific control mode in which the duty cycle of the drive signal is adjusted to change a value of the current through a first motor. The processor performs, when changing the relative rotational phase through execution of the specific control mode, an abnormality diagnosis for the variable valve lift mechanism based on a comparison between the current value at the first motor and a reference current value. The processor sets the reference current value in accordance with a rotation angle of the output shaft of a second motor.

A two-stroke internal combustion engine has an engine block having a cylinder block and a cylinder head. The cylinder block defines a cylinder, an exhaust passage, and an exhaust valve passage. The engine also has a piston, an exhaust valve actuator operatively connected to at least one of the cylinder block and the cylinder head, and a reciprocating exhaust valve disposed at least in part in the exhaust valve passage. The exhaust valve has a shaft operatively connected to a valve actuator, and a blade connected to the shaft. A channel is defined along a face of the blade. The channel and a wall of the exhaust valve passage together define at least in part a valve passage. The valve passage permits flow of exhaust gas along the face of the blade. A width of the valve passage is at least a third of a width of the blade.

A method of providing diagnostic information for an electromagnetic latch assembly (122) includes providing a pulse to a circuit (200) that include one or more electromagnetic latch assemblies. The circuit (200) includes coils (199) of the electromagnetic latch assemblies. Each coil is inductively coupled with an armature (131) that is mechanically coupled to a latch pin (118). The circuit (200) is pulsed and a DC current in the circuit (200) that results from the pulse is measured over a first interval to determine a primary response. The current in the circuit (200) over a second interval is measured to determine a reference response. A second pulse may be used to generate the current for the reference response. The primary response and the reference response are compared to provide diagnostic information relating to position or movement of one or more of the latch pins (118).

A method for adjusting a valve lash in an internal combustion engine includes receiving a first signal generated by a sensor secured to the internal combustion engine, the first signal being indicative of a closing of a valve, receiving a second signal indicative of at least one of an engine speed of the internal combustion engine or a position of a camshaft of the internal combustion engine, and automatically determining an adjusted amount of lash associated with the valve based on the received first signal and the received second signal. The method also includes comparing the adjusted amount of lash to at least one predetermined threshold, and providing, in response to determining that the adjusted amount of lash is greater than the at least one predetermined threshold, a valve lash re-adjustment notification.

Aspects of the present invention relate to a control advanced system for controlling a valve actuator for an internal combustion engine, the control system comprising one or more controllers, the control system being configured to: receive a requirement signal retarded indicative of a requirement for valve actuation with a first valve timing characteristic; receive an expected flow signal indicative of expected mass flow rate of air, associated with the first valve timing characteristic; control the valve actuator to provide the first valve timing characteristic; receive an actual flow signal indicative of actual mass flow rate of air, associated with the control of the valve actuator; cause comparison of the actual flow signal with the expected flow signal; and cause an action to be performed in dependence on the comparison, wherein the action comprises a compensation action and/or a fault reporting action and/or determining camshaft phase information.