Fuel injection control of an internal combustion engine requires an optimized fuel amount that can be burned completely with oxygen in intake air to be supplied, but the oxygen concentration in the atmospheric air is affected by humidity. By separately calculating a dry air flow rate that directly affects the oxygen amount and a humidity flow rate that is a change factor of the oxygen concentration in the intake air of the internal combustion engine, the fuel can be supplied to the cylinder of the internal combustion engine at an optimized air-fuel ratio. In addition, highly precise control involving EGR for flowback of a part of the exhaust gas flowing in the exhaust pipe to the intake pipe can also be achieved.

A sensor device is disposed in an intake passage through which intake air flows to an internal combustion engine. The sensor device includes a humidity sensor that generates a signal according to a humidity of the intake air flowing through the intake passage. A choke portion is defined in the intake passage to decrease a cross-sectional area of the intake passage. The humidity sensor is arranged on the choke portion.

An estimation method to determine the concentration of recirculated exhaust gas present in a cylinder of an internal combustion engine; the concentrations of recirculated exhaust gas in a gas mixture flowing through an intake duct are periodically stored in a buffer; a first instant is determined, in which a programming of a following combustion in the cylinder is carried out; an advance time is determined, which elapses between the first instant and a second instant in the future, in which air will be taken into the cylinder for the following combustion in the cylinder; a transport time is determined; a third instant in the past is determined by subtracting from the first instant an amount of time which is equal to the difference between the transport time and the advance time; and the concentration of recirculated exhaust gas present in the cylinder in the second instant is estimated depending on a concentration of recirculated exhaust gas contained in the buffer (30) and corresponding to the third instant.

A physical quantity measuring device detects a physical quantity of gas flowing in a flow passage. The physical quantity measuring device includes a sensor element that outputs a detection signal according to the physical quantity, a case that is provided to the flow passage and houses the sensor element, and a protrusion that protrudes from a passage wall surface facing the flow passage. The case includes a measurement chamber that houses the sensor element and an inflow port that is configured to cause a part of gas flowing in the flow passage to flow into the measurement chamber therethrough. The protrusion is configured to guide gas flowing along the passage wall surface toward the inflow port.

In order to provide a highly precise and highly responsive humidity detection means with which diagnosis is easy, this control device for an internal combustion engine is characterized in that two or more sensors for detecting the humidity of the atmosphere or a gas mixed with the atmosphere are provided in the middle of the flow in an intake air passage of the internal combustion engine, at least one of these sensors being a relative humidity sensor for detecting the relative humidity, at least one other of the sensors being an absolute humidity sensor for detecting the absolute humidity, and the relative humidity sensor being arranged upstream from the absolute humidity sensor.

Mobile oil-free multi-stage compressor device which includes at least a low-pressure stage compressor element with an inlet and an outlet and a high-pressure stage compressor element with an inlet and an outlet, wherein the outlet of low-pressure stage compressor element is connected to the inlet of the high-pressure stage compressor element through a line. The line includes an intercooler which is provided with a controllable fan. In addition, the compressor device is provided with a control unit that is configured to control a controllable fan to control the temperature at an outlet of the intercooler on the basis of the dewpoint in the line.

A method (30) of protecting an internal combustion engine (12) of a vehicle (10) from damage by induction of liquid, the method (30) comprising: detecting (31) liquid in a gas induction system (11) to the engine (12); and causing (32) valve control means (44) to at least perform one or both of the following: inhibiting gas intake into a combustion chamber (47) of the engine (12) during a gas intake stage (50) of a combustion cycle of the combustion chamber (47); causing gas exhaust from a combustion chamber (47) of the engine (12) during a gas compression stage (51) of the combustion cycle of the combustion chamber (47), wherein the valve control means (44) comprises at least one of a hydraulic circuit or an electromagnetic actuator for controlling, at least in part, the inhibiting gas intake into a combustion chamber (47) and/or at least one of a hydraulic circuit or an electromagnetic actuator for controlling, at least in part, the causing gas exhaust from a combustion chamber (47).

In an engine, an intake duct is provided with an intercooler disposed downstream of an intake air compressor. An EGR pipe is provided with an EGR valve and an EGR cooler. An ECU determines a generation of a condensed water in the EGR cooler, the generation of the condensed water in a merging portion where a fresh air and an EGR gas merge with each other, and the generation of the condensed water in the intercooler. When it is determined that the condensed water is generated in any of these portions, the ECU performs a corresponding countermeasure for restricting the generation of the condensed water.

A temperature sensor and a relative humidity sensor are placed in an environment allowing air to flow and are displaced in an upstream-downstream direction of the airflow. An absolute humidity acquisition unit acquires absolute humidity of air from outputs from the temperature sensor and the relative humidity sensor. A delay adjustment unit delays an output from one of the temperature sensor and the relative humidity sensor placed upstream and to reconcile change-behaviors of outputs from the temperature sensor and the relative humidity sensor in response to a state change in air. The absolute humidity acquisition unit acquires the absolute humidity based on the output from the other of the temperature sensor and the relative humidity sensor placed downstream and an output acquired from the one sensor placed upstream and delayed in the delay adjustment unit.

An intake manifold for an internal combustion engine, comprising: a at least one air intake opening connected to an inner chamber, and a plurality of outlet pipes connected to the inner chamber, wherein each outlet pipe is provided with an outlet opening adapted for a sealed connection with a cylinder head of an internal combustion engine, wherein the intake manifold is injection moulded in a plastic material, wherein the intake manifold comprises at least one water injection nozzle moulded into the intake manifold. The advantage of the invention is that a cost-efficient water injection system for a combustion engine is provided.