Abstract: An internal combustion engine according to this invention is provided with intake ports each of which is formed to guide a flow of inducted air in a particular direction. Each intake port includes, in the vicinity of its corresponding intake opening to a combustion chamber, a bent port portion bent at a greater curvature than a port portion on a side upstream of the bent port portion. The bent port portion has a greater inner diameter than the inner diameter of the corresponding intake opening, whereby air can be inducted in a sufficient amount without deterioration to the directing function for air to be inducted into the combustion chamber.

Abstract: A stratified burning internal combustion engine according to this invention is equipped with an intake port and a fuel feed device so that stratified tumble flows of different fuel concentrations can be formed in a combustion chamber. An ignition device is provided in the combustion chamber to ignite at least one of the tumble flows, said at least one tumble flow being rich in fuel. To promote the stratified tumble flows, a top wall of a piston has an inclined wall. This makes it possible to strengthen the tumble flows, whereby the stratification of an air-fuel mixture in the combustion chamber can be improved further to permit lean burn at a larger air/fuel ratio.

Abstract: A vertical vortex, namely, a reverse tumble flow is formed inside a cylinder of an internal combustion engine to form an intake air flow for smooth intake and exhaust in the internal combustion engine and also to promote atomization of fuel and mixing of air and fuel in a combustion chamber. To form this reverse tumble flow, a downstream portion of an intake passage is formed extending toward a central axis of the cylinder. To promote the formation of the swirl and further to form the combustion chamber as an efficient compact combustion chamber, a recessed portion is formed in a top wall of a piston. The top wall of the piston is provided with a raised portion at a location adjacent to the recessed portion, whereby, in the vicinity of top dead center of the piston, a squish is produced in a direction flowing toward a side of a spark plug in the efficient combustion chamber.

Abstract: An internal combustion engine according to this invention is provided with intake ports and an injector. The intake ports are designed to form stratified tumble flows of different fuel concentrations in a combustion chamber. A spark plug is arranged in the combustion chamber to ignite one of the tumble flows, which one tumble flow is rich in fuel. Each intake port is provided with a longitudinal partition which divides an interior of the intake port into two passages. These longitudinal partitions are formed in such a way that, of the air-fuel tumble flows formed around the spark plug, the tumble flow closest to the spark plug is formed of a richer air-fuel mixture. Each longitudinal partition is arranged only on a side upstream of a valve stem of an intake valve in the corresponding intake port, so that a sufficient amount of intake air can be obtained while extremely minimizing a reduction in the actual cross-sectional flow area.

Abstract: This invention relates to an intake port structure for an internal combustion engine. It is an object of the present invention to increase the strength of tumbling without lowering the maximum flow rate. An intake port (44) is constructed broader in a tumble-flow-side half (44a) than in the other half (44b) to have an intake air flow through the intake port (44) off-centered toward the side of a tumble flow, whereby an intake air flow from the intake port (44) promotes the tumble flow.

Abstract: An ignition timing controller is furnished for use in a spark-ignition internal combustion engine. The controller includes a device for setting the ignition timing of the engine in accordance with the state of operation of the engine and another device for actuating an ignition system on the basis of the ignition timing set by the ignition timing setting device. The ignition timing setting device is constructed of a device for estimating the wall temperature of a combustion chamber of the engine from a variable, which indicates the quantity of combustion energy of the engine, and another device for calculating the ignition timing from the wall temperature of the combustion chamber estimated by the wall temperature estimating device.

Abstract: A stratified-combustion internal combustion engine according to the present invention comprises at least two intake ports situated on one side of a combustion chamber, guide passages connected individually to the intake ports, a fuel injector disposed in one of the guide passages. Each guide passage has a straight region extending over a predetermined length from its corresponding intake port. Thus, an air-fuel mixture and air, guided by the respective straight regions of the guide passages to be supplied through their corresponding intake ports to the combustion chamber, flow along the axial direction of a cylinder bore, thereby forming barrel swirl flow separated in layers from each other.

Abstract: A method and device for determining and controlling the condition of a spark ignition internal combustion engine involves detecting a physical value of combustion varying in association with combustion in the combustion chamber, then calculating the heat evolution rate from the physical value, and then determining the adjusting the combustion condition in dependence on the falling area of the heat evolution rate.