Systems and methods for managing excessive intake flow path pressure and counter flow are implemented to support enhanced engine braking applications, such as 2-stroke or 1.5-stroke engine braking implementations where the intake flow path may be exposed to excessive transient pressures in the combustion chamber during activation or deactivation of an engine brake. Intake throttle, exhaust gas recirculation (EGR) valve, intake manifold blow-off valve, compressor bypass valve, exhaust throttle, turbocharger geometry or turbocharger waste gate may be controlled to effectuate counter flow management separately or in combination. Excessive transient conditions may also be prevented or managed by sequential valve motion in which brake motion activation occurs first and then exhaust valve main event deactivation occurs second. Delay between brake activation and main event deactivation may be facilitated using mechanical and/or hydraulic implements as well as electronically.

Disclosed is a combustion engine and method for engine braking therein including an intake air channel having a first pressure, a first inlet valve between the intake air channel and the cylinder volume, an exhaust air channel having a second pressure, a first outlet valve between the cylinder volume and the exhaust air channel, and a storage reservoir having a third pressure higher than the first and second pressures, the storage reservoir being arranged in controllable fluid communication with the cylinder volume. The method takes place during two-stroke cycle and includes: displacing the piston from upper dead centre (UDC) towards lower dead centre (LDC), keeping the first inlet valve open during at least part of the travel from UDC to LDC, displacing the piston from LDC towards UDC, and keeping the fluid communication between the storage reservoir and cylinder volume open during at least a part of such travel.

An internal combustion engine is provided. Facing pistons eliminate a cylinder head, thereby reducing heat losses through a cylinder head. Facing pistons also halve the stroke that would be required for one piston to provide the same compression ratio, and the engine can thus be run at higher revolutions per minute and produce more power. An internal sleeve valve is provided for space and other considerations. A combustion chamber size-varying mechanism allows for adjustment of the minimum size of an internal volume to increase efficiency at partial-power operation. Variable intake valve operation is used to control engine power.

A two-stroke, opposed-piston engine includes a cylinder with an inlet piston controlled inlet port and an exhaust piston controlled exhaust port, the cylinder defining a combustion chamber with the inlet piston and the exhaust piston, a charge air channel in flow communication with the inlet port, a conduit extending directly from the combustion chamber to the charge air channel, and a valve arranged to selectively open and close flow communication through the conduit.

The present invention discloses a control method of variable stroke engine for reforming high-octane fuel under the FCE mode, the ECU connected to the engine controls the amount of fuel injected from the flexible cylinder injector to the flexible cylinder and controls the switch state of inlet valve and exhaust valve of the flexible cylinder, so that the flexible cylinder can be switched between two-stroke mode and four-stroke mode according to the actual engine operating conditions; when the engine is at a small load and needs to promote combustion stability, the flexible cylinder injector injects a rich fuel with equivalence ratio greater than 1 into the flexible cylinder, the flexible cylinder is at two-stroke mode; when the engine is at a large load and needs sufficient power output, the flexible cylinder injector injects a conventional fuel into the flexible cylinder, said flexible cylinder is at four-stroke mode.

A method for controlling a powertrain of a vehicle, the powertrain comprising: an engine comprising mutually independently operable valves, the engine being configured to be operated in a four-stroke operation mode, and a drivetrain comprising a transmission,
the method comprising: while operating the engine in the four-stroke operation mode, identifying that a critical situation applies or is expected to apply, in which a fast downshift of the transmission is required, initiating a downshift process in response to the identification of the critical situation, during at least a part of the downshift process, increasing an engine speed by controlling at least the mutually independently operable valves of the engine such that the engine is temporarily operated in a two-stroke operation mode.

A two-stroke engine (1) is disclosed comprising a cylinder (2), a piston (3) arranged to reciprocate in the cylinder (2), a crankcase (5), a fuel injector (7) configured to inject fuel into the crankcase (5), an air inlet (9) connected to the crankcase (5), and a stratified scavenging intake (11) connected to the cylinder (2). The engine (1) comprises a throttle (13) configured to control the amount of air supplied to the air inlet (9) and to the stratified scavenging intake (11). The present disclosure further relates to handheld power tool (50) comprising an engine (1).

A 2-cycle internal combustion engine in which the intake cycle begins before and ends after the exhaust cycle, resulting in a longer power stroke, increased torque and greater efficiency is disclosed herein. In the preferred embodiment, the 2-cycle engine has a power stroke of about 160 degrees, an exhaust stage of about 70 degrees, and an intake cycle of about 110-115 degrees.

A two-stroke engine with a supercharger is provided that can prevent occurrence of abnormal combustion under high load and can improve fuel efficiency when compression self-ignition combustion is carried out under low load, and spark ignition combustion is carried out under high load. When an operation state of an engine body is in a high-load side operation range, an intake variable valve mechanism and an exhaust variable valve mechanism are actuated to retard at least closing timing of an intake valve and at least opening timing of an exhaust valve from those in the case where the operation state of the engine body is in a low-load side operation range at the same engine speed as the engine speed detected by engine speed detection means while particular conditions are satisfied.

A two-stroke engine with a supercharger is provided that can prevent occurrence of abnormal combustion under high load and can improve fuel efficiency when compression self-ignition combustion is carried out under low load, and spark ignition combustion is carried out under high load. When an operation state of an engine body is in a high-load side operation range, an intake variable valve mechanism and an exhaust variable valve mechanism are actuated to retard at least closing timing of an intake valve and at least opening timing of an exhaust valve from those in the case where the operation state of the engine body is in a low-load side operation range at the same engine speed as the engine speed detected by engine speed detection means while particular conditions are satisfied.