Swirl-inducing apparatus for internal combustion engines

Claim 1

Apparatus for imparting a swirl to a flow of intake gas entering a cylinder of an internal combustion engine, the apparatus including an engine having a cylinder block which contains at least one cylinder, a cylinder head fastened to the block and having an intake valve seat for each cylinder, and a swirl-inducing suction passage for each cylinder, each suction passage having an upstream end communicating with a source of intake gas and a downstream end opening into the respective cylinder through the corresponding intake valve seat, wherein the improvement comprises: throttle valve means mounted in each suction passage close to the intake valve port for opening and shutting the suction passage to regulate the rate of flow of intake gas therethrough, the swirl-inducing suction passage between the throttle valve means and the intake valve being in the form of a helical port and the throttle valve means being a butterfly valve arranged to rotate about an approximately horizontal diametral axis transverse to the intake mixture flow direction in the suction passage, the valve having a downstream-opening portion on the upper side of the suction passage and an upstream-opening portion on the lower side of the suction passage, the apparatus further comprising means for preventing flow past the upstream-opening portion in the general working range from idling through low-speed, low-load operation to concentrate the flow on the upper side of the passageway only through an initial opening range corresponding to engine operating conditions from idling through low speed, light-load, for converging the intake gas to flow eccentrically along said upper side of the passage from the throttle valve means to the intake valve seat to enhance the swirl imparted by the swirl-producing suction passage at low flow volumes, and said suction passage being opened on both sides of said approximately horizontal diametral axis upon further rotation of the throttle valve beyond said initial opening range, to distribute flow through substantially the entire intake port cross section at higher engine speeds and loads.