A blow-by gas leak diagnostic device includes a first PCV flow path, a second PCV flow path, a fresh air inlet, a pressure measurement unit, a first valve that opens and closes the first PCV flow path, a second valve that opens and closes the second PCV flow path, a third valve that opens and closes the fresh air inlet, a valve control unit, and a leak diagnosis unit. The valve control unit controls an opening degree of the third valve when a downstream side of an intake manifold with respect to a throttle valve has a negative pressure, and the second valve is in a closed state. The leak diagnosis unit diagnoses presence or absence of a leak in the first PCV flow path on the basis of an inner pressure of the first PCV flow path measured by the pressure measurement unit.

The invention relates to an oil decantation system (1) comprising: (i) a separator device (6) designed to trap the oil droplets (107) that are present in a flow of a blow-by gas (110); and (ii) a jet pump (5) positioned upstream of the separator device (6) and designed to accelerate and draw the flow of the blow-by gas (110) before it enters said separator device (6).

A ventilation apparatus of an internal combustion engine of the invention ventilates a chain chamber by recirculating blow-by gas to an intake passage through a blow-by gas recirculation pipe and introducing air into the chain chamber through an air introduction pipe. The air introduction pipe is secured to a head cover wall portion which corresponds to a portion of a head cover wall which defines the chain chamber.

An internal combustion engine may be used to compress natural gas for vehicle fuel. The engine may contain a plurality of gas compression cylinders, at least one standard combustion cylinder to drive the compression cylinders, and a common crankshaft in a crankcase coupling the compression cylinders and the at least one standard combustion cylinder. Some combustible gas being compressed may leak past the piston rings of the compression cylinders into the engine crankcase posing a safety concern. This invention eliminates this concern by actively flushing the crankcase at a higher rate than normal.

The invention relates to a method for controlling the oil pressure of an oil pump (40, 140) in a combustion engine (100). The combustion engine (100) comprises a crankcase (11) and a separator (14, 114) for separating oil present in a blow-by gas from the crankcase (11). The method comprises the step (201) of providing oil pressure demand for a set of different engine operation conditions, the oil pressure demand defining the theoretical required oil pressure of the oil pump (40, 140); the step (203) of controlling the oil pressure of the oil pump (40, 140) based on the oil pressure demand for at least one engine operation condition in the set of different engine operation conditions; the step (205) of driving the separator (14, 114) using oil from the oil pump (40, 140), the oil being pressurized based on the oil pressure demand.

An abnormality assessment device includes an on-off valve that shuts an intake path on an upstream side of a connection portion of a breather line with respect to the intake path and an abnormality assessment element that assesses abnormality of the breather line. The abnormality assessment element assesses abnormality of the breather line based on a difference between an intake flow rate that is detected by an intake flow rate sensor and a target intake flow rate in a case where the on-off valve is closed.

Methods and systems are provided for diagnosing a clogged crankcase and performing a crankcase clean out. In one example, a method of operating an engine system including an engine includes measuring a crankcase pressure, and in response to the crankcase pressure increasing above a threshold pressure, determining a position of a clogged oil separator in a crankcase, and directing fluid to flow through the clogged oil separator and into the crankcase until a flow rate of the fluid through the clogged oil separator and into the crankcase increases above a threshold flow rate.

Methods and systems are provided for monitoring a crankcase ventilation system. In one example, a method may include diagnosing a breach in a crankcase vent tube based on a regression of measurements of pressure in the crankcase vent tube. The regression allows the pressure measurements to be extended across an entire range of operating air flows and the breach may be identified by comparing the regressed pressure measurements to expected crankcase vent tube pressures.

Various examples are provided related to crankcase ventilation for moisture removal and explosion mitigation. In one example, a combustion engine includes a crankcase with a combustion chamber; a crankcase vent for venting crankcase gas from the crankcase; and an active crankcase ventilation system for supplying supplemental air to the crankcase. The crankcase gas can include a mixture of blowby gas from the combustion chamber and the supplemental air in a ratio that reduces or eliminates condensation of water in the crankcase gas. The combustion engine can be a hydrogen engine or other type of engine.

A blow-by gas leak diagnostic device includes a first PCV flow path, a second PCV flow path, a fresh air inlet, a pressure measurement unit, a first valve that opens and closes the first PCV flow path, a second valve that opens and closes the second PCV flow path, a third valve that opens and closes the fresh air inlet, a valve control unit, and a leak diagnosis unit. The valve control unit controls an opening degree of the third valve when a downstream side of an intake manifold with respect to a throttle valve has a negative pressure, and the second valve is in a closed state. The leak diagnosis unit diagnoses presence or absence of a leak in the first PCV flow path on the basis of an inner pressure of the first PCV flow path measured by the pressure measurement unit.