Abstract: An exhaust gas purification system for an internal combustion engine includes an engine capable of fuel combustion at lean air-fuel ratios, a catalyst constructed of zeolite carrying at least one kind of metal selected from transition metals and noble metals to reduce NOx under oxidizing conditions and in the presence of HC, engine operating condition detecting means for detecting the current engine operating condition, engine operating range determining means for determining whether or not the current engine operating condition is within an insufficient HC amount range, and an HC amount control means for controlling the amount of HC included in the exhaust gas when the engine operating range determining means determines that the engine operating condition is within the insufficient HC amount range.

Abstract: A two-stroke engine including a pair of intake valves. A masking wall is provided for each intake valve to mask the valve opening between the valve seat and the peripheral portion of the intake valve, which is located on the exhaust valve side, for the entire time for which the intake valve is open. The exhaust valves open earlier than the intake valves, and the exhaust valves and the intake valves are closed at substantially the same time.

Abstract: An internal combustion engine comprising a spark plug arranged at the center of the inner wall of the cylinder head, and a fuel injector arranged on the periphery of the inner wall of the cylinder head. A depression extending from the position beneath the spark plug to the position beneath the tip portion of the fuel injector is formed on the top face of the piston, and fuel is injected toward the depression. When the engine is operating under a heavy load, the fuel moving along the axis of injection impinges upon the concaved inner wall of the depression at substantially a right angle. When the engine is operating under a light load, the injection time is retarded, and at this time, the fuel moving along the axis of injection impinges upon the concaved inner wall of the depression at an acute angle.

Abstract: An internal combustion engine having an air blast valve which injects fuel together with pressurized air in the form of a conical shaped spray of fuel. A depression is formed on the top face of the piston, and the conical shaped spray of fuel is injected from the air blast valve toward the depression. The longitudinal width of the depression in the moving direction of the spray of fuel is larger than the transverse width of the depression in the direction perpendicular to the moving direction of the spray of fuel, and the opposing side walls of the depression, which define the transverse width of the depression, are positioned slightly outward from the side face of the conical shaped spray of fuel.

Abstract: A sheet tobacco producing apparatus comprises a mixer, a kneader, a crusher, and a shaping machine. The mixer mixes tobacco chips with auxiliary substances including water, to produce wet round pieces. The kneader has a pair of rollers for kneading the wet round pieces to form a sheet intermediate. The crusher crushes the sheet intermediate to form crushed wet round pieces. The shaping machine has a pair of rollers for forming a final sheet product from the crushed pieces. Since the tobacco raw material is deformed from the sheet intermediate which is obtained after once kneaded, to round pieces again, it is easy to take the material iinto the gap between the rollers of the shaping machine, whicn increases the manufacturing speed of the apparatus.

Abstract: A two-stroke engine having an intake valve and an exhaust valve which are arranged on the cylinder head. A masking wall is formed on the inner wall of the cylinder head to mask the valve opening between the valve seat and the peripheral portion of the intake valve, which is located on the exhaust valve side, for the entire time for which the intake valve is open.

Abstract: In an internal combustion engine, a heater for heating an air-fuel ratio sensor provided in the exhaust gas flow passage is controlled in accordance with a parameter of a load of the engine. That is, the heater is turned ON when the load parameter is not larger than a predetermined value, and the heater is turned OFF when the load parameter is larger than the predetermined value. The turning OFF of the heater is delayed with a predetermined delay time when the engine rotational speed is lower than a predetermined value, and the turning ON of the heater is delayed with the predetermined delay time when the engine rotational speed is higher than the predetermined value. Thus, the number of times that the heater is turned ON and OFF is decreased, thereby prolonging the life of the heater.

Abstract: A cylinder head gasket arranged between a cylinder head and a cylinder block in an internal combustion engine. The cylinder head gasket has a core web of steel with hooks arranged between facing sides of a pair of gasket plates made of a heat resistant resilient material, such as asbestos or graphite. Grommet rings are fitted to edges of openings in the web and the gasket plates aligned corresponding to the respective cylinder bores. The web has regions adjacent to the inner periphery of the aligned openings and located substantially inside of the grommet member rings, the regions containing no hooks, or containing hooks having a reduced height.

Abstract: A fuel injection control apparatus for use of an engine. The apparatus varies a minimum amount of fuel to be injected into the engine according to such conditions as the engine speed increases or decreases. When the engine speed increases, a first minimum amount of fuel is set in low and intermediate engine speed zones and the first minimum amount is converted to a second minimum amount of fuel which is less than the first minimum amount in a high engine speed zone. Contrary to this, when the engine speed decreases, the second minimum amount of fuel is set in high and intermediate engine speed zones, and the second minimum amount of fuel is converted into the first minimum amount of fuel in the low engine speed zone. Thus, according to the increase or decrease in an engine speed, a minimum amount of fuel is varied with a hysteresis.