A turbocharger engine includes a dual stage turbocharger in which a first turbo unit is disposed on the upstream side of a second turbo unit on an exhaust passage. The turbocharger is disposed in such a manner that a second turbine shaft of the second turbo unit is far from an engine output shaft than a first turbine shaft of the first turbo unit in a plan view in an axis direction of a cylinder. Further, a second turbine is rotated clockwise around an axis thereof in a side view when the turbocharger is viewed from the side of the turbine, and an intra-turbine passage is disposed on the side of an engine body than the second turbine shaft.

An apparatus, system, and method are disclosed for optimizing a valve orifice shape. According to one representative embodiment, a method includes determining a specified relationship between a valve position and an output characteristic, and determining an orifice profile. The method also includes determining a relationship of an orifice area to the output characteristic. Further, the method includes shaping an orifice in a valve based on the orifice profile and the specified relationship between the valve position and the output characteristic. According to the method, the valve should approximately exhibit the specified relationship.

A turbocharger includes a two-stage serial compressor having a first impeller and a second impeller affixed to a shaft and arranged in series for a two-stage compression of air, an exhaust gas-driven turbine having a turbine wheel affixed to the shaft, and an electric motor mounted on the shaft for assisting the turbine in rotatably driving the compressor.

A turbocharger includes a two-stage serial compressor having a first impeller and a second impeller affixed to a shaft and arranged in series for a two-stage compression of air, an exhaust gas-driven turbine having a turbine wheel affixed to the shaft, and an electric motor mounted on the shaft for assisting the turbine in rotatably driving the compressor.

A supercharging system includes: a first supercharger including a first compressor for compressing air to be supplied to an engine; a second supercharger including a second compressor for further compressing air compressed by the first compressor; and a controller for controlling the first supercharger and the second supercharger. At least one of the first supercharger or the second supercharger further includes an electric motor for driving the first compressor or the second compressor. At least one of the first supercharger or the second supercharger further includes a turbine configured to be rotary driven by exhaust gas from the engine, and a nozzle vane configured to adjust a flow-path area of the exhaust gas flowing into the turbine. The controller includes: an electric motor control part configured to, if an amount of charge of a battery for supplying electric power to the electric motor is less than a first threshold, set an upper limit value of an output command value for the electric motor to be lower than when the amount of charge of the battery is not less than the first threshold, or switch operation of the electric motor to regenerative operation; and a vane control part configured to, if the amount of charge of the battery is less than the first threshold, control an opening degree of the nozzle vane so that the flow-path area decreases with a control of the electric motor by the electric motor control part.

A supercharging system includes: a first supercharger including a first compressor for compressing air to be supplied to an engine and a motor for driving the first compressor; a leakage current measuring part for measuring a leakage current of the motor; and a first controller for controlling the first supercharger. The first controller includes a motor control part configured to, when a measurement result by the leakage current measuring part is not less than a first threshold, set an upper limit value of an output command value for the motor to be lower than when the measurement result is less than the first threshold, and to control an output of the motor within a range which does not exceed the upper limit value.

A supercharging system includes: a first supercharger including a first compressor for compressing air to be supplied to an engine and a motor for driving the first compressor; a leakage current measuring part for measuring a leakage current of the motor; and a first controller for controlling the first supercharger. The first controller includes a motor control part configured to, when a measurement result by the leakage current measuring part is not less than a first threshold, set an upper limit value of an output command value for the motor to be lower than when the measurement result is less than the first threshold, and to control an output of the motor within a range which does not exceed the upper limit value.

A supercharging system for an internal combustion engine provided with a plurality of turbochargers includes: a state-amount detection part configured to detect a state amount related to an operational state of the internal combustion engine; and a control part configured to control at least one of an intake flow-passage switching valve or an exhaust flow-passage switching valve so that an operation mode transitions from a first operation mode to a second operation mode if the state amount is at least a threshold selected corresponding to the state amount on the basis of a first threshold function, and so that the operation mode transitions from the second operation mode to the first operation mode if the state amount is less than a threshold selected corresponding to the state amount on the basis of a second threshold function. The first threshold function and the second threshold function are set to be different from each other.

A supercharging system for an internal combustion engine provided with a plurality of turbochargers includes: a state-amount detection part configured to detect a state amount related to an operational state of the internal combustion engine; and a control part configured to control at least one of an intake flow-passage switching valve or an exhaust flow-passage switching valve so that an operation mode transitions from a first operation mode to a second operation mode if the state amount is at least a threshold selected corresponding to the state amount on the basis of a first threshold function, and so that the operation mode transitions from the second operation mode to the first operation mode if the state amount is less than a threshold selected corresponding to the state amount on the basis of a second threshold function. The first threshold function and the second threshold function are set to be different from each other.

In a two-stage supercharging electric-assist turbocharger, a first compressor wheel, a rotor of an electric motor, a second compressor wheel, and a turbine wheel are coaxially coupled to a same, common shaft member, in that order. A compressor housing is structured to define therein a communicating passage to accommodate the electric motor in the communicating passage. A first water jacket is formed in at least one rib integrally formed with an outer periphery of a motor housing and also serving as a radiating fin, for forced-cooling air flowing through the communicating passage. A second water jacket is formed in a motor housing for forced-cooling a stator of the electric motor. A third water jacket is formed in an intermediate housing constructing a part of the compressor housing for forced-cooling a control unit configured to control the electric motor.