Abstract: An internal combustion engine of an automotive vehicle has a cylinder block formed with a cylinder bore, and a piston is fitted in the bore and reciprocates in it. A cylinder head is affixed to the cylinder block and defines a combustion chamber in cooperation with the piston and the cylinder bore. This cylinder head is formed with a portion which in cooperation with a portion of the piston defines a squish area of the combustion chamber, and with a coolant passage which substantially follows through the cylinder head adjacent to the squish area so as directly to cool the squish area. The coolant passage is of substantially the same cross sectional area along its extent. Thereby, the flow of coolant through the coolant passage is kept substantially uniform and at uniform speed throughout its extent, and cooling of the squish area is enhanced.

Abstract: A piston for an internal combustion engine formed as an integrally cast article having a crown portion and a hollow cylindrical side wall portion, wherein the crown portion is formed with a transverse hollow space, radially outside portions of which are axially traversed by integrally formed ribs, the hollow space being adapted to be circulated by lubricant for the purpose of cooling the crown portion. To supply lubricant into and to drain lubricant from the hollow space, a transverse wall portion formed in the crown portion on the inner side of the hollow space is formed with a lubricant inlet opening and at least one lubricant outlet opening, preferably at portions located between the ribs.

Abstract: A piston assembly for an internal combustion engine is made up from a piston main body and a lubricant reservoir defining member. The piston main body has a cup-shaped structure including a crown portion and a hollow cylindrical wall portion joining thereto, two piston pin bosses being formed at opposite sides of the wall portion. The lubricant reservoir defining member is made from a shelf plate main body portion which provides a central lubricant reservoir and two openings on its opposite sides, and two major legs extending from the shelf plate main body portion and each formed with a hole surrounded by an annular portion. Each of the annular portions is engaged with an inner end portion of a corresponding one of the bosses and surrounds the piston pin hole thereof.

Abstract: A piston assembly for an internal combustion engine is made up from a piston main body and a lubricant reservoir defining member. The piston main body has a cup shaped structure including a crown portion and a hollow cylindrical wall portion joining thereto. The lubricant reservoir defining member includes a shelf plate main body portion formed with first and second depressions which define first and second lubricant reservoirs, and is securely mounted within the cup shaped piston structure with the shelf plate portion generally to and opposing the piston crown. The ratio of the surface area of the first lubricant reservoir to the surface area of the second lubricant reservoir is less than the ratio of the volume of the first lubricant reservoir to the volume of the second lubricant reservoir. Lubricant is supplied more towards the first lubricant reservoir and is drained more from the second reservoir.

Abstract: An engine comprising an intake port which has a separating wall projecting downwardly from the upper wall of the intake port. The separating wall defines a helical portion, an inlet passage portion tangentially connected to the helical portion, and a bypass passage interconnecting the inlet passage portion and the helical portion. The separating wall has an upstream end portion centrally located between the opposed side walls of the intake port. A rotary valve is arranged in the bypass passage and is actuated by a vacuum-operated diaphragm apparatus. The rotary valve is opened when the amount of air fed into the cylinder of the engine is increased beyond a predetermined value.

Abstract: An engine comprising an intake port which has a separating wall projecting downwardly from the upper wall of the intake port. The separating wall defines a helical portion, an inlet passage portion tangentially connected to the helical portion, and a bypass passage interconnecting the inlet passage portion to the helical portion. A rotary valve is arranged in the bypass passage and actuated by a vacuum operated diaphragm apparatus. The rotary valve is opened when the amount of air fed into the cylinder of an engine is increased beyond a predetermined value.

Abstract: An engine comprising an intake port which has a separating wall projecting downwardly from the upper wall of the intake port. The separating wall defines a helical portion, an inlet passage portion tangentially connected to the helical portion, and a bypass passage interconnecting the inlet passage portion and the helical portion. The intake port has a bottom wall having a transverse width which is approximately equal to the diameter of the valve head of the intake valve. The opposed peripheral edges of the bottom wall are located on the extensions of the tanget lines of the outer periphery of the valve head of the intake valve. A rotary valve is arranged in the bypass passage and is actuated by a vacuum-operated diaphragm apparatus. The rotary valve is opened when the amount of air fed into the cylinder of the engine is increased beyond a predetermined value.

Abstract: An engine comprising an intake port which has a separating wall projecting downwardly from the upper wall of the intake port. The separating wall defines a helical portion, an inlet passage portion tangentially connected to the helical portion, and a bypass passage interconnecting the inlet passage portion and the helical portion. A rotary valve is arranged in the inlet portion of the bypass passage so that the axis of the rotary valve is substantially parallel to the axis of the stem of the intake valve. The rotary valve is actuated by a vacuum-operated diaphragm apparatus and is opened when the amount of air fed into the cylinder of the engine is increased beyond a predetermined value.

Abstract: An engine comprising an intake port which has a separating wall projecting downwardly from the upper wall of the intake port. The separating wall defines a helical portion, an inlet passage portion tangentially connected to the helical portion, and a bypass passage interconnecting the inlet passage portion and the helical portion. The separating wall extends to near the side wall of the helical portion and defines a narrow passage portion therebetween. The width of the upper wall of the inlet passage portion is gradually reduced towards the narrow passage portion. A rotary valve is arranged in the bypass passage and is actuated by a vacuum-operated diaphragm apparatus. The rotary valve is opened when the amount of air fed into the cylinder of the engine is increased beyond a predetermined value.

Abstract: An engine comprising an intake port which has a separating wall projecting downward from the upper wall of the intake port. The separating wall defines a helical portion, an inlet passage portion tangentially connected to the helical portion, and a bypass passage interconnecting the inlet passage portion to the helical portion. A rotary valve is arranged in the bypass passage and actuated by a vacuum operated diaphragm apparatus. The rotary valve is opened when the amount of air fed into the cylinder of an engine is increased beyond a predetermined value. The separating wall has a height which is equal to approximately half the height of the intake port in the vicinity of the rotary valve.

Abstract: An engine comprising an intake port which has a separating wall projecting downwardly from the upper wall of the intake port. The separating wall defines a helical portion, an inlet passage portion tangentially connected to the helical portion, and a bypass passage interconnecting the inlet passage portion to the helical portion. A rotary valve is arranged in the bypass passage and actuated by a vacuum operated diaphragm apparatus. The rotary valve is opened when the amount of air fed into the cylinder of an engine is increased beyond a predetermined value. A downwardly projecting rib is formed on the bottom face of the separating wall. The rib extends toward the helical portion from the rotary valve.

Abstract: An internal combustion engine has a cylinder head formed with a wedge shaped cylinder head recess which has on its one side closer to a spark plug a steeply inclined roof surface of about 38.degree. to 40.degree. inclination and on its other side a gently inclined roof surface of about 5.degree. to 20.degree. inclination formed with an intake valve opening, and a piston formed with a piston recess which generally mates with the cylinder head recess and which has on its one side closer to the spark plug an inclined side surface of about 45.degree. inclination. The planar surface portion of the piston crown and the planar surface portion of the cylinder head on opposite sides of the recessed portions mutually define a relatively large squish area on the side of the gently inclined roof surface and a relatively small squish area on the side of the steeply inclined roof surface. A helical port is connected to the intake valve opening so as to generate a swirl flow of air-fuel mixture in the combustion chamber.

Abstract: An engine comprising an intake port which has a separating wall projecting downward from the upper wall of the intake port. The separating wall defines a helical portion, an inlet passage portion tangentially connected to the helical portion, and a bypass passage interconnecting the inlet passage portion to the helical portion. A rotary valve is arranged in the bypass passage and actuated by a vacuum operated diaphragm apparatus. The rotary valve is opened when the amount of air fed into the cylinder of an engine is increased beyond a predetermined value. A conical shaped groove is formed on the bottom wall of the intake port. The lower end of the rotary valve is located in the groove.

Abstract: A high compression type internal combustion engine comprising a cylinder head having a flat inner wall, and a piston having a flat top face. The flat inner wall and the flat top face form a squish area therebetween. A recess having a lung-shaped cross-section is formed in the cylinder head. A shallow groove is formed on the flat inner wall of the cylinder head so as to extend from the intake valve to the recess. An exhaust valve is arranged on the bottom of the recess. The squish area comprises a first squish area portion and a second squish area portion. The first squish area portion has an area which is about four times the area of the second squish area portion. A spark plug is arranged in the recess at a position near the first squish area portion and remote from the second squish area portion.

Abstract: A fuel injection type internal combustion engine comprising a cylinder head having a flat inner wall, and a piston having a flat top face. The flat inner wall and the flat top face form a squish area therebetween. A recess having a lung shaped cross-section is formed in the cylinder head. A shallow groove is formed on the flat inner wall of the cylinder head so as to extend from the intake valve to the recess. The exhaust valve is arranged on the bottom of the recess. A depression connected to the recess is formed on the shallow groove. The spark plug is arranged in the depression. The cylinder head has a portion located between the recess and the intake passage. A fuel injector is arranged in the intake passage. The nozzle of the fuel injector is directed to an inner wall portion of the intake passage, which is located near the recess.

Abstract: In an internal combustion engine, the combination of a cylinder head with a plane lower surface and a cavity, a piston with a plane upper surface and a cavity, the plane surfaces of the piston and the cylinder head cooperating to form a squish area on one side of the cylinder bore, and a spark plug protruding into the combustion chamber defined by the cavities so that its igniting tip lies substantially in the squish plane on the other side of the cylinder bore.

Abstract: A high compression type internal combustion engine comprising a cylinder head having a flat inner wall, and a piston having a flat top face. The flat inner wall and the flat top face form a squish area therebetween. A recess having a lung shaped cross-section is formed in the cylinder head. A shallow groove is formed in the flat inner wall of the cylinder head so as to extend from the intake valve to the recess. The exhaust valve is arranged on the top of the recess. A depression connected to the recess is formed in the shallow groove. The spark plug is arranged in the depression.