A method and control device for automatically identifying knocking in an internal combustion engine, wherein, in a predefined measurement time frame, a signal of the knocking sensor is received and evaluated with respect to a criterion for detecting knocking. A basic threshold value predefined for the identification of knocking is modified by a predefined variable interference factor, which depends on a relative point in time at which an inlet valve of at least one of the cylinders closes in relation to a predefined reference point. A signal based on the sensor signal is only identified as knocking if it reaches at least the modified basic threshold value.

The present disclosure relates to an internal combustion engine system including an internal combustion engine comprising a cylinder; an air guide arranged to guide air to the cylinder; at least one inlet valve adapted to selectively provide a fluid communication between said air guide and said cylinder; and an inlet valve actuation assembly for actuating said at least one inlet valve, said inlet valve actuation assembly being adapted to actuate said at least one inlet valve in accordance with one of at least two lift modes during a combustion cycle of said internal combustion engine. The internal combustion engine system is adapted to be operated in a first operation mode in which said throttle arrangement is arranged in an at least partially closed condition and said inlet valve actuation assembly actuates said at least one inlet valve according to a second of the at least two lift modes.

The present disclosure relates to internal combustion engines. The teachings thereof may be embodied in a method for determining a torque reserve for an internal combustion engine during a change of an operating state. The method may include: operating the internal combustion engine in the first operating state; determining a rotational speed; determining a torque; determining an air mass setpoint value based on the rotational speed and the torque in the second operating state; calculating a torque setpoint value depending on the rotational speed and the air mass setpoint value in the first operating state; and determining a torque reserve for the transition from the first operating state to the second operating state using based on the torque and on the torque setpoint value.

There is provided a controller for an internal combustion engine that includes an exhaust gas recirculation device. The exhaust gas recirculation device includes an exhaust gas recirculation passage, which connects a portion of the intake passage located at a downstream side of the throttle valve with an exhaust passage, a recirculation valve, which opens and closes the exhaust gas recirculation passage, and an actuator, which drives and opens the recirculation valve. The controller includes a processor configured to execute a fuel cut-off process that stops fuel injection from the fuel injection valve, to open the recirculation valve when the fuel cut-off process is executed, and to execute a pressure increase process that increases pressure of the portion of the intake passage at the downstream side of the throttle valve before opening the recirculation valve.

An engine includes a cylinder body, a cylinder head, and an ignition device including spark plugs. The engine also includes an intake device connected to intake ports, an exhaust device connected to exhaust ports, pistons, and a crankshaft connected to the pistons by connecting rods. Explosion intervals of the cylinders are 270, 180, 90, and 180 as crank angles. The engine further includes a discomfort eliminator which, when the engine speed is lower than a predetermined value, makes the indicated mean effective pressure of at least one of two cylinders having an explosion interval of 90 lower than the indicated mean effective pressures of the other cylinders having an explosion interval of not 90. The engine causes unequal-interval explosions but produces little change in the driving energy per unit time during an operating state in which an occupant is liable to feel torque fluctuations.

The object of the present invention is to provide a compact engine. An engine has a two-stage turbocharger provided with a high-pressure turbocharger and a low-pressure turbocharger. The high-pressure turbocharger and the low-pressure turbocharger are separately disposed on the gear case side and the flywheel side in along direction of a main body respectively. An intake pipe and an exhaust pipe connecting the high-pressure turbocharger with the low-pressure turbocharger are separately and respectively disposed on right side and left side in a transverse direction of the main body.

An operating range boundary for switching a cam for driving an intake valve (drive cam) is changed in a direction of decreasing an engine load if a target EGR rate is predicted to increase across the contour line shown in FIG. 3. By changing the boundary, the drive cam is switched from a large cam to a small cam before an operating point is transferred from a partitioned range R.sub.2 to a partitioned range R.sub.1. When the small cam is selected as the drive cam, suction efficiency is frequently lowered as compared to a case where the large cam is selected as the drive cam. Therefore, the drive cam is switched to the small cam before the operating point is transferred from the partitioned range R.sub.2 to the partitioned range R.sub.1, thereby enabling the suction efficiency to be lowered in many cases.

When a stop request to the engine is issued, it is determined whether or not all of the drive cams are large cams. When it is determined that at least one of the small cams is included in the drive cams, the engine is continued to drive for a while and a switch control for switching the drive cams from the small cams to the large cams is executed within the duration. A self-holding type solenoid is used to switch between the small cams and the large cams. In the switch control, a permission to stop the engine is output at a timing when the pin protrudable section of the final cylinder #2 has elapsed.

A control system for controlling operation of an internal combustion engine is configured to: receive a first request signal indicative of first torque demand; determine a schedule defining an opening timing of the intake valve and a closing timing of the intake valve of a cylinder of the internal combustion engine in dependence on the first torque demand; and cause the intake valve to open in accordance with the schedule. The control system is also configured to, during a period in which the intake valve is open: receive a second torque request signal indicative of a second torque demand different to the first torque demand; determine an updated schedule defining an updated closing timing of the intake valve in dependence on the second torque demand; and cause the intake valve to close in accordance with the updated schedule.

A lift amount variable mechanism is configured to switch a cam for driving an intake valve (drive cam) between two types of intake cams in lift amount (i.e. a large lift cam and a small lift cam). In a first embodiment of this disclosure, the lift amount variable mechanism is controlled by an ECU so that the small lift cam is selected as the drive cam for control that promotes activation of an exhaust gas cleaning catalyst (catalyst warm-up control).