A straddle-type vehicle comprises a supercharging device which compresses intake-air, an air-intake chamber which is disposed downstream of the supercharging device, a pressure rising suppressing valve which is actuated by a pressure and connected to an inner space of the air-intake chamber, the pressure rising suppressing valve being configured to open the inner space of the air-intake chamber to a relief passage, in a case where a difference between a preset pressure in a pilot space and a pressure in the air-intake chamber reaches a predetermined value or more, a control valve which is electrically actuated and is capable of performing switching of a space to be in communication with the pilot space, between a high-pressure space and a low-pressure space; and a valve controller which provides to the control valve an operation command for controlling the control valve.

Embodiments for an engine coupled to a first turbocharger and a second turbocharger are provided. One example includes responsive to a first condition, deactivating a first turbine of the first turbocharger and meeting a boost demand via operation of the second turbocharger, and responsive to deactivating the first turbine, increasing a pressure at a compressor-side end of a bearing arrangement of a shaft of the first turbocharger. In this way, oil leakage from the bearing arrangement may be reduced.

Embodiments for an engine coupled to a first turbocharger and a second turbocharger are provided. One example includes responsive to a first condition, deactivating a first turbine of the first turbocharger and meeting a boost demand via operation of the second turbocharger, and responsive to deactivating the first turbine, increasing a pressure at a compressor-side end of a bearing arrangement of a shaft of the first turbocharger. In this way, oil leakage from the bearing arrangement may be reduced.

An engine system for a motor vehicle is provided. The engine system includes a first exhaust-gas turbine in a first turbocharger driven by exhaust gas from the engine, a second exhaust-gas turbine in a second turbocharger driven by exhaust gas from the engine, a bypass coupled upstream and downstream of the first exhaust-gas turbine, and a pneumatic charge pressure control device including a bypass valve positioned in the bypass and a charge pressure control valve pneumatically coupled to the bypass valve and an intake line downstream of a first compressor included in the first turbocharger, the pneumatic charge pressure control device further including an adaptation unit pneumatically coupled to the bypass valve and an exhaust line upstream of the second exhaust-gas turbine.

An engine system for a motor vehicle is provided. The engine system includes a first exhaust-gas turbine in a first turbocharger driven by exhaust gas from the engine, a second exhaust-gas turbine in a second turbocharger driven by exhaust gas from the engine, a bypass coupled upstream and downstream of the first exhaust-gas turbine, and a pneumatic charge pressure control device including a bypass valve positioned in the bypass and a charge pressure control valve pneumatically coupled to the bypass valve and an intake line downstream of a first compressor included in the first turbocharger, the pneumatic charge pressure control device further including an adaptation unit pneumatically coupled to the bypass valve and an exhaust line upstream of the second exhaust-gas turbine.

An engine system having donor cylinders and non-donor cylinders is disclosed. The engine system may have a first intake manifold configured to distribute air into the non-donor cylinders, and a second intake manifold configured to distribute air into the donor cylinders. The engine system may also have a first exhaust manifold configured to discharge exhaust from the non-donor cylinders to the atmosphere, and a second exhaust manifold separate from the first exhaust manifold and configured to recirculate exhaust from the donor cylinders to the first intake manifold. The engine system may further have an orifice disposed in between the first intake manifold and the second intake manifold. The orifice may be configured to regulate a flow rate of fluid flowing from the first intake manifold to the second intake manifold. The engine system may further have a controller configured to selectively control the orifice in response to a desired exhaust gas recirculation operating condition.

A control method for an internal combustion engine, the internal combustion engine including a valve timing control mechanism on at least an intake side and configured to control an operation of the valve timing control mechanism on the intake side during acceleration, the method including, calculating a relational expression between an intake valve timing, the intake valve timing being an operation timing of an intake valve, and a cylinder air charge amount in a range in which the intake valve timing can be advanced or retarded within a predetermined calculation cycle from a current value, calculating a target air charge amount, the target air charge amount being a target value of the cylinder air charge amount during the acceleration, based on an operating state of the internal combustion engine, calculating a target value of the intake valve timing corresponding to the target air charge amount from the relational expression for each calculation cycle, and setting a command signal for the valve timing control mechanism on the intake side based on a calculated target value of the intake valve timing.

A control method for an internal combustion engine, the internal combustion engine including a valve timing control mechanism on at least an intake side and configured to control an operation of the valve timing control mechanism on the intake side during acceleration, the method including, calculating a relational expression between an intake valve timing, the intake valve timing being an operation timing of an intake valve, and a cylinder air charge amount in a range in which the intake valve timing can be advanced or retarded within a predetermined calculation cycle from a current value, calculating a target air charge amount, the target air charge amount being a target value of the cylinder air charge amount during the acceleration, based on an operating state of the internal combustion engine, calculating a target value of the intake valve timing corresponding to the target air charge amount from the relational expression for each calculation cycle, and setting a command signal for the valve timing control mechanism on the intake side based on a calculated target value of the intake valve timing.

A control device for an internal-combustion engine includes circuitry. The circuitry is configured to calculate, in accordance with an operating state of the internal-combustion engine, a basic supercharging pressure of intake gas generated by a supercharger provided in the internal-combustion engine. The circuitry is configured to acquire a flow rate change state parameter that correlates with a change state of the flow rate of the intake gas controlled by a flow rate control mechanism provided in the internal-combustion engine. The circuitry is configured to calculate a correction value in accordance with the flow rate change state parameter. The circuitry is configured to calculate an estimated supercharging pressure of the intake gas by correcting the basic supercharging pressure with the correction value. The circuitry is configured to control operation of the internal-combustion engine using the estimated supercharging pressure.

A control device for an internal-combustion engine includes circuitry. The circuitry is configured to calculate, in accordance with an operating state of the internal-combustion engine, a basic supercharging pressure of intake gas generated by a supercharger provided in the internal-combustion engine. The circuitry is configured to acquire a flow rate change state parameter that correlates with a change state of the flow rate of the intake gas controlled by a flow rate control mechanism provided in the internal-combustion engine. The circuitry is configured to calculate a correction value in accordance with the flow rate change state parameter. The circuitry is configured to calculate an estimated supercharging pressure of the intake gas by correcting the basic supercharging pressure with the correction value. The circuitry is configured to control operation of the internal-combustion engine using the estimated supercharging pressure.