Abstract: In an upstream portion from a valve connecting surface that is formed in an opening of an intake port to a combustion chamber, an upper wall surface of the intake port continues from an upstream side end of the valve connecting surface and extends substantially straight and diagonally with respect to a ceiling surface on the intake port side. In addition, a cross-sectional shape of the portion in the intake port in a direction perpendicular to an axial direction of the intake port is a flat shape with an axis in a transverse direction being a long axis.

Abstract: An object of the invention is to provide an internal combustion engine that suppresses a blow-by phenomenon in an overlap period, while allowing for formation of a favorable swirl flow in a combustion chamber. In the internal combustion engine, a housing space is formed in an opening of an exhaust port to the combustion chamber to be more recessed in a cylinder head than an exhaust port-side ceiling surface. A bevel portion of an exhaust valve is placed in the housing space in a valve closed state of the exhaust valve. A valve contact surface is formed on an inner wall surface of the housing space.

Abstract: With regard to an internal combustion engine having a tumble flow formed in a cylinder, an object of the invention is to intensify the tumble flow. There is provided an internal combustion engine having a pent-roof type combustion chamber. In a predetermined area in the vicinity of an opening of an intake port to a combustion chamber, an upper wall surface of the intake port is extended approximately linearly while being inclined to an intake port-side ceiling surface more downward than a normal direction of the intake port-side ceiling surface in a side view. In a partial area in the predetermined area of the intake port, a distance between lateral wall surfaces on a left side and on a right side of the intake port is gradually increased toward downstream in a top view.

Abstract: In an upstream portion from a valve connecting surface that is formed in an opening of an intake port to a combustion chamber, an upper wall surface of the intake port continues from an upstream side end of the valve connecting surface and extends substantially straight and diagonally with respect to a ceiling surface on the intake port side. In addition, a cross-sectional shape of the portion in the intake port in a direction perpendicular to an axial direction of the intake port is a flat shape with an axis in a transverse direction being a long axis.

Abstract: An object of the invention is to provide an internal combustion engine that suppresses a blow-by phenomenon in an overlap period, while allowing for formation of a favorable swirl flow in a combustion chamber. In the internal combustion engine, a housing space is formed in an opening of an exhaust port to the combustion chamber to be more recessed in a cylinder head than an exhaust port-side ceiling surface. A bevel portion of an exhaust valve is placed in the housing space in a valve closed state of the exhaust valve. A valve contact surface is formed on an inner wall surface of the housing space.

Abstract: With regard to an internal combustion engine having a tumble flow formed in a cylinder, an object of the invention is to intensify the tumble flow. There is provided an internal combustion engine having a pent-roof type combustion chamber. In a predetermined area in the vicinity of an opening of an intake port to a combustion chamber, an upper wall surface of the intake port is extended approximately linearly while being inclined to an intake port-side ceiling surface more downward than a normal direction of the intake port-side ceiling surface in a side view. In a partial area in the predetermined area of the intake port, a distance between lateral wall surfaces on a left side and on a right side of the intake port is gradually increased toward downstream in a top view.

Abstract: An air intake device 40 comprises: a surge tank 44 having an upper tank chamber 50, a lower tank chamber 52, and a communication portion 56; a first intake pipe 46 having communication with the upper tank chamber 50; a second intake pipe 48 having communication with the lower tank chamber 52; and a valve 58 disposed in the lower tank chamber 52, the valve 58 being displaced between a closed position, in which an internal space of the lower tank chamber 52 is divided into a main space 60 having communication with the second intake pipe 48 and a sub-space 62 facing the communication portion 56, and an open position, in which the main space 60 and the sub-space 62 are integrated with each other.

Abstract: A port that communicates an inside of a combustion chamber of an internal combustion engine with an outside of the combustion chamber includes a throat portion that has at least a portion of a truncated cone shape, a valve seat portion that is connected to one end portion of the throat portion to communicate the throat portion with the inside of the combustion chamber, and a passage portion that is connected to the other end portion of the throat portion to communicate the throat portion with the outside of the combustion chamber.

Abstract: In an intake device for an internal combustion engine, in which a valve body rotatable about a valve shaft is provided within an intake passage and by which an intake flow is controlled, the valve shaft is eccentric with a center of the valve body and is supported at a position eccentric with a center of the intake passage. When the valve body rotates, a half open state is formed from a fully closed state via a fully open state. The butterfly-type intake control valve are simply altered, so that the fully closed state, the fully open state, and the half open state can be formed and the vortex flow can be formed into the cylinder.

Abstract: An intake port structure of an internal combustion engine includes an intake port, a valve shaft provided in proximity to an inner wall of the intake port, and an airflow control valve having a proximal end which is pivotally supported on the valve shaft and a distal end which becomes part of the inner wall of the intake port when the airflow control valve is fully opened. The inner wall of the intake port has a recess into which the airflow control valve is partially or entirely retracted when the airflow control valve is fully opened. The recess has a flow smoothing portion located downstream of the proximal end.

Abstract: An intake port structure for an internal combustion engine according to the invention includes a valve shaft provided in an intake port; and an airflow control valve that is supported by the valve shaft at one end of the airflow control valve or at a position near the one end. A gap is formed between the airflow control valve and a wall surface of the intake port, which is positioned on one side of the valve shaft. Because intake airflow passes through the gap that is formed, the generation of a deposit is suppressed, and the locking of the airflow control valve is avoided.

Abstract: In an intake system for an internal combustion engine wherein a partition plate is provided within an intake pipe in a longitudinal direction so that an inside is divided into a first intake passage, which is an upper side passage of the above described intake pipe, and a second intake passage, which is a lower side passage of the above described intake pipe, and an intake control valve for opening and closing the second intake passage is provided, the partition plate has holes which connect the first intake passage to the second intake passage and allow fuel on a lower surface of the partition plate to be sucked out to the first intake passage. When an intense tumble flow is created in the first intake passage in the intake system, an air flow toward the first intake passage from the second intake passage is created in the holes so that the fuel that adheres to the partition plate can be sucked out.

Abstract: A variable intake device includes an intake pipe through which air flows towards a combustion chamber of an engine, defining a first streamline at an intermediate portion of the pipe, a short-circuit pipe connected at the intermediate portion, defining a second streamline crossing the first streamline at the connected other end, and a valve arranged at the short-circuit pipe adjacent to the intermediate portion. The valve includes a valve body regulating air flow. When the valve allows air flow merging into the intake pipe from the short-circuit pipe, the valve body is positioned to extend in a direction between the extending direction of the first streamline indicated by arrow and the extending direction of the second streamline indicated by arrow. By such a configuration, a variable intake device having pressure loss at the intake path sufficiently reduced can be provided.

Abstract: In an intake system for an internal combustion engine wherein a partition plate is provided within an intake pipe in a longitudinal direction so that an inside is divided into a first intake passage, which is an upper side passage of the above described intake pipe, and a second intake passage, which is a lower side passage of the above described intake pipe, and an intake control valve for opening and closing the second intake passage is provided, the partition plate has holes which connect the first intake passage to the second intake passage and allow fuel on a lower surface of the partition plate to be sucked out to the first intake passage. When an intense tumble flow is created in the first intake passage in the intake system, an air flow toward the first intake passage from the second intake passage is created in the holes so that the fuel that adheres to the partition plate can be sucked out.

Abstract: In an intake device for an internal combustion engine, in which a valve body rotatable about a valve shaft is provided within an intake passage and by which an intake flow is controlled, the valve shaft is eccentric with a center of the valve body and is supported at a position eccentric with a center of the intake passage. When the valve body rotates, a half open state is formed from a fully closed state via a fully open state. The butterfly-type intake control valve are simply altered, so that the fully closed state, the fully open state, and the half open state can be formed and the vortex flow can be formed into the cylinder.

Abstract: An intake port structure for an internal combustion engine according to the invention includes a valve shaft provided in an intake port; and an airflow control valve that is supported by the valve shaft at one end of the airflow control valve or at a position near the one end. A gap is formed between the airflow control valve and a wall surface of the intake port, which is positioned on one side of the valve shaft. Because intake airflow passes through the gap that is formed, the generation of a deposit is suppressed, and the locking of the airflow control valve is avoided.

Abstract: A variable intake device includes an intake pipe through which air flows towards a combustion chamber of an engine, defining a first streamline at an intermediate portion of the pipe, a short-circuit pipe connected at the intermediate portion, defining a second streamline crossing the first streamline at the connected other end, and a valve arranged at the short-circuit pipe adjacent to the intermediate portion. The valve includes a valve body regulating air flow. When the valve allows air flow merging into the intake pipe from the short-circuit pipe, the valve body is positioned to extend in a direction between the extending direction of the first streamline indicated by arrow and the extending direction of the second streamline indicated by arrow. By such a configuration, a variable intake device having pressure loss at the intake path sufficiently reduced can be provided.

Abstract: An air intake device 40 comprises: a surge tank 44 having an upper tank chamber 50, a lower tank chamber 52, and a communication portion 56; a first intake pipe 46 having communication with the upper tank chamber 50; a second intake pipe 48 having communication with the lower tank chamber 52; and a valve 58 disposed in the lower tank chamber 52, the valve 58 being displaced between a closed position, in which an internal space of the lower tank chamber 52 is divided into a main space 60 having communication with the second intake pipe 48 and a sub-space 62 facing the communication portion 56, and an open position, in which the main space 60 and the sub-space 62 are integrated with each other.

Abstract: An intake port structure of an internal combustion engine includes an intake port, a valve shaft provided in proximity to an inner wall of the intake port, and an airflow control valve having a proximal end which is pivotally supported on the valve shaft and a distal end which becomes part of the inner wall of the intake port when the airflow control valve is fully opened. The inner wall of the intake port has a recess into which the airflow control valve is partially or entirely retracted when the airflow control valve is fully opened. The recess has a flow smoothing portion located downstream of the proximal end.

Abstract: An air intake device includes: a surge tank 14 having an internal space divided into a first space and a second space; a first intake manifold 20 including a plurality of intake branch pipes 16 protruding from the surge tank 14 via a funnel 18 and communicating with the first space, the first intake manifold 20 supplying air to cylinders on a first of two cylinder banks; and a second intake manifold 22 including a plurality of intake branch pipes 16 protruding from the surge tank 14 via the funnel 18 and communicating with the second space, the second intake manifold 22 supplying air to cylinders on a second of the two cylinder banks. The funnel 18 has a substantially rectangular transverse cross-sectional shape.