Abstract: An ethylene base polymer and a preparation method of an ethylene base polymer characterized in use of a catalyst comprising a chromium amide compound, a solid inroganic oxide calcined at 100 to 500.degree. C. and alumoxane. According to the present invention, an ethylene base polymer with a wide molecular weight distribution, excellent shock and environmental stress cracking resistances, causing no melt fracture, and suitable for film forming and blow molding can be effectively prepared.

Abstract: An ethylenic polymerization catalyst comprising (A) a chromium compound, (B) a carrier, (C) aluminoxane, and (D) a transition metal compound comprising a group having conjugated .pi. electron as a ligand, wherein said chromium compound (A) is not calcined; and a process for producing an ethylenic polymer comprising a step of polymerizing a monomer comprising ethylene in the presence of the ethylenic polymerization catalyst.

Abstract: Internal combustion engine having an intake port formed in cylinder head and a first and second intake passages both connected with said intake port. The intake passages are respectively provided with throttle valves and the throttle valve in the second intake passage is opened only under a heavy load operation. The ignition timing is advanced when the throttle valve in the second intake passage has been brought into operation.

Abstract: An exhaust gas recirculation system has at least two recirculation lines to permit recirculation of a large quantity of exhaust gas when required and in which recirculation of exhaust gas is reduced or completely cut off in accordance with particular engine operating conditions.

Abstract: Internal combustion engine having an intake port formed in cylinder head and first and second intake passages both connected with the intake port. The intake passages are respectively provided with throttle valves and the throttle valve in the second intake passage is opened only under a heavy load operation. The ignition timing is advanced or an additional supply of fuel is provided in the transient period wherein the throttle valve in the first intake passage has reached substantially fully open position and the throttle valve in the second intake passage has started to open so as to supplement any decrease in the engine output in this period.

Abstract: An exhaust gas recirculation device in which exhaust gas from the engine of a vehicle, for example, may be recirculated via two separate lines to portions of a carburetor which are upstream and downstream of a throttle valve, to permit a suitably large amount of exhaust gas to be recirculated when necessary and which includes control means which stops the flow of gas in both lines when the engine is being warmed up, and stops the flow of gas in the upstream recirculation line only when engine load, engine speed, or vehicle speed is high, or when there is a risk of icing in the carburetor, whereby the disadvantages of recirculated exhaust gas during particular engine operating conditions are avoided.

Abstract: An improved air-fuel mixture intake system for use in a internal combustion engine having a light load side intake passage and a heavy load side intake passage which are joined each other in the vicinity of an intake valve of the engine. The intake system includes engine deceleration detecting means, a first on-off valve provided in a fuel supplying path of a light load side carburetor, an air supplying passage opened into the heavy load side intake passage at downstream of a heavy load side carburetor throttle valve, and a second on-off valve provided in the air supplying passage for reduction of noxious hydrocarbon formation and prevention of after-burning, with suppression of undesirable knocking.