A valve system comprising a valve chamber at a junction of an inlet port, an outlet port and a bypass port, the inlet port configured for fluid communication with exhaust gas, the outlet port configured for fluid communication with an inlet of a turbine, and the bypass port configured for fluid communication with an exhaust aftertreatment device; a rotary valve comprising a valve rotor which rotates about a valve axis within the valve chamber between a first position to permit gas flow through the bypass port and a second position to block gas flow. At least one of the valve rotor and the valve chamber comprises a protrusion and the other comprises a recess, wherein, in the first position, the protrusion and recess are spaced from one another, and, in the second position the recess receives the protrusion such that gas flow between the protrusion and recess is substantially prevented.

A valve system comprising a valve chamber at a junction of an inlet port, an outlet port and a bypass port, the inlet port configured for fluid communication with exhaust gas, the outlet port configured for fluid communication with an inlet of a turbine, and the bypass port configured for fluid communication with an exhaust aftertreatment device; a rotary valve comprising a valve rotor which rotates about a valve axis within the valve chamber between a first position to permit gas flow through the bypass port and a second position to block gas flow. At least one of the valve rotor and the valve chamber comprises a protrusion and the other comprises a recess, wherein, in the first position, the protrusion and recess are spaced from one another, and, in the second position the recess receives the protrusion such that gas flow between the protrusion and recess is substantially prevented.

The invention concerns a method for controlling a compression release brake mechanism in an combustion engine comprising an air inlet system and an exhaust manifold connected to a turbocharger provided with a variable turbine geometry (VTG) turbine, said exhaust manifold further comprising an exhaust gas recirculation (EGR) channel for recirculation of exhaust gas towards the air inlet system, wherein said turbine is further connected to a back pressure valve (BPV) provided in an exhaust channel, the method comprising determining a desired exhaust manifold gas pressure level on the basis of a measured engine speed and a desired braking torque; continuously monitoring a set of control parameters, including at least two of cylinder pressure, exhaust manifold pressure, turbine speed and turbine expansion ratio; controlling said BPV and said VTG by said control parameters, to drive one of the control parameters to a set maximum level; and controlling the EGR by said control parameters in a closed loop to allow exhaust gas to recirculate towards the air inlet system while driving a second of the set of control parameters to a set maximum level.

Methods and systems are provided for engine braking in a vehicle. In one example, a method may include deactivating fueling to at least one cylinder of an engine, increasing an air mass provided to the engine via an electric boosting device, and adjusting an exhaust valve opening timing of the at least one cylinder in response to a request for engine braking. In this way, an amount of engine braking torque may be increased with reduced wear to engine system components.

Methods and systems are provided for engine braking in a vehicle. In one example, a method may include deactivating fueling to at least one cylinder of an engine, increasing an air mass provided to the engine via an electric boosting device, and adjusting an exhaust valve opening timing of the at least one cylinder in response to a request for engine braking. In this way, an amount of engine braking torque may be increased with reduced wear to engine system components.

The invention relates to controlling engine braking of an internal combustion engine wherein the method includes setting the engine in an engine braking mode comprising i) interrupting fuel supply to a first cylinder, ii) restricting the flow of gas through an exhaust duct using an adjustable flow restricting member, and iii) controlling inlet and exhaust valves of the first cylinder in a compression-release mode comprising controlling the valves to compress gas in a combustion chamber when the piston moves towards the top dead center position (TDC) and release compressed gas into the exhaust duct when the piston is near the TDC. The method includes, prior to ii and iii: reducing a total gas mass flow rate through the engine by controlling, for at least one of valve, reducing a valve lift and/or adjusting a timing of a valve opening or closing so as to reduce the gas mass flow rate through the cylinder.

A method for learning braking step threshold values of a sustained-action brake includes detecting a braking requirement setpoint, controlling the sustained-action brake with the braking requirement setpoint to generate a braking effect variable of the sustained-action brake, and detecting a sustained-action brake actual braking effect variable and a maximum sustained-action brake braking effect. The method additionally includes forming a braking effect variable coefficient that characterizes a ratio of the sustained-action brake actual braking effect variable and the maximum sustained-action brake braking effect variable that results from control of the sustained-action brake with the braking requirement setpoint, and assigning the braking effect variable coefficient to a braking step of the sustained-action brake such that each braking step is assigned only one braking effect variable. Additionally, the method includes storing the braking requirement setpoint that results in the braking effect variable coefficient.

A method for learning braking step threshold values of a sustained-action brake includes detecting a braking requirement setpoint, controlling the sustained-action brake with the braking requirement setpoint to generate a braking effect variable of the sustained-action brake, and detecting a sustained-action brake actual braking effect variable and a maximum sustained-action brake braking effect. The method additionally includes forming a braking effect variable coefficient that characterizes a ratio of the sustained-action brake actual braking effect variable and the maximum sustained-action brake braking effect variable that results from control of the sustained-action brake with the braking requirement setpoint, and assigning the braking effect variable coefficient to a braking step of the sustained-action brake such that each braking step is assigned only one braking effect variable. Additionally, the method includes storing the braking requirement setpoint that results in the braking effect variable coefficient.

An embodiment device includes an auxiliary brake including a retarder selectively operated to consume an output of a transmission to generate a braking force and an engine brake selectively operated to increase a flow resistance of an exhaust gas discharged from an engine to generate a braking force, a gas flow volume controller configured to open or close flow paths of an engine intake line and an engine exhaust line, and a controller configured to compare a first braking force difference with a predetermined reference braking force when the auxiliary brake is operated during coasting traveling and to determine and control an opening rate of the gas flow volume controller based on the first braking force difference and an engine speed when the first braking force difference is less than the reference braking force.

A control method for use in an engine braking maneuver for an internal combustion engine (ICE) system including a turbocharger having a variable-nozzle turbine (VNT), the ICE system further including an exhaust flap disposed in an exhaust line downstream of the variable-nozzle turbine. Prior to closing the exhaust flap, the VNT vanes are first parked in a fully open position. After the exhaust flap closes, the vanes are pivoted to a fully closed position and are continuously urged against a hard stop as long as the exhaust flap is closed. Termination of engine braking entails pivoting the vanes back to the fully open position, whereupon the exhaust flap is opened.