Abstract: A wastegate valve device according to at least one embodiment is a wastegate valve device disposed on a bypass passage bypassing a turbine of a turbocharger arranged on an exhaust gas passage of an engine, including: a valve seat surface formed at an outlet of the bypass passage; and a wastegate valve body which includes a support arm supported rotatably about an axis and a valve body supported by the support arm, the valve body being configured to come into and out of contact with the valve seat surface in accordance with rotation of the support arm. In the wastegate valve device according to at least one embodiment, the valve seat surface is inclined with respect to a direction orthogonal to an axial direction of the bypass passage, as viewed from a direction of the above-described axis.

Abstract: A turbocharger according to an embodiment is a turbocharger including a turbine housing for housing a turbine wheel rotary driven by an exhaust gas, a bearing housing for housing a rotational shaft on which the turbine wheel is mounted, the bearing housing being adjacent to the turbine housing, and a wastegate portion including a bypass passage and a valve body, the bypass passage allowing the exhaust gas to bypass the turbine wheel, the valve body being able to adjust a flow rate of the exhaust gas flowing through the bypass passage. In the turbine housing, a scroll passage for supplying the exhaust gas to the turbine wheel is formed by casting, at least on a radially outer side of the turbine wheel. A fastening portion for fastening the turbine housing and the bearing housing is disposed on a radially outer side of the scroll passage.

Abstract: A turbocharger according to an embodiment is a turbocharger including a turbine housing for housing a turbine wheel rotary driven by an exhaust gas, a bearing housing for housing a rotational shaft on which the turbine wheel is mounted, the bearing housing being adjacent to the turbine housing, and a wastegate portion including a bypass passage and a valve body, the bypass passage allowing the exhaust gas to bypass the turbine wheel, the valve body being able to adjust a flow rate of the exhaust gas flowing through the bypass passage. In the turbine housing, a scroll passage for supplying the exhaust gas to the turbine wheel is formed by casting, at least on a radially outer side of the turbine wheel. A fastening portion for fastening the turbine housing and the bearing housing is disposed on a radially outer side of the scroll passage.

Abstract: A turbocharger includes: at least two scroll passages, and a first range of the nozzle flow passage into which the exhaust gas flowing through the first scroll passage is introduced does not overlap with a second range of the nozzle flow passage into which the exhaust gas flowing through the second scroll passage is introduced, in a circumferential direction of the nozzle flow passage.

Abstract: A two-stage turbo system includes: a high-pressure stage turbocharger having a high-pressure stage turbine disposed in an exhaust passage of an engine; and a low-pressure stage turbocharger which includes a low-pressure stage turbine disposed downstream of the high-pressure stage turbine in the exhaust passage, and which is larger in size than the high-pressure stage turbocharger. The low-pressure stage turbine includes at least two scroll passages including a first scroll passage and a second scroll passage, which together form a scroll part for introducing exhaust gas into a nozzle flow passage of the low-pressure stage turbine. The scroll part is configured such that a first range of the nozzle flow passage into which the exhaust gas passing through the first scroll passage is introduced does not overlap with a second range of the nozzle flow passage into which the exhaust gas passing through the second scroll passage is introduced, in a circumferential direction of the nozzle flow passage.

Abstract: A turbocharger includes: at least two scroll passages, and a first range of the nozzle flow passage into which the exhaust gas flowing through the first scroll passage is introduced does not overlap with a second range of the nozzle flow passage into which the exhaust gas flowing through the second scroll passage is introduced, in a circumferential direction of the nozzle flow passage.

Abstract: A two-stage turbo system includes: a high-pressure stage turbocharger having a high-pressure stage turbine disposed in an exhaust passage of an engine; and a low-pressure stage turbocharger which includes a low-pressure stage turbine disposed downstream of the high-pressure stage turbine in the exhaust passage, and which is larger in size than the high-pressure stage turbocharger. The low-pressure stage turbine includes at least two scroll passages including a first scroll passage and a second scroll passage, which together form a scroll part for introducing exhaust gas into a nozzle flow passage of the low-pressure stage turbine. The scroll part is configured such that a first range of the nozzle flow passage into which the exhaust gas passing through the first scroll passage is introduced does not overlap with a second range of the nozzle flow passage into which the exhaust gas passing through the second scroll passage is introduced, in a circumferential direction of the nozzle flow passage.