Abstract: An intake system construction for an internal combustion engine having a generally straight first intake port, a generally helical second intake port, both intake ports opening to one combustion chamber, and a common intake passage for supplying fuel-air mixture to the two intake ports. A control valve is fitted in the first intake port for selectively throttling the first intake port at low load operation of the engine, and a deflection valve is fitted in the commmon intake passage for selectively constricting intake flow through the common intake passage to deflect the flow toward the second intake port and away from the first intake port at low load operation of the engine, so that fuel accumulation on the cotrol valve closed at low load operation of the engine is avoided.

Abstract: A positive photoresist composition in the form of solution which comprises a resin soluble in an aqueous alkaline solution, a 1,2-quinonediazide derivative as a photosensitizer, and at least one anti-halation agent in amounts of about 1 to about 10 parts by weight in relation to 100 parts by weight of the resin in the composition, the anti-halation agent being selected from the group consisting of dyestuffs of specific structures.

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 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 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.