Odd-cylinder V-type internal combustion engine

Abstract

A V-type internal combustion engine, having (2n+1) (n is natural number) cylinders, is provided with a crank shaft having n common crank pins Kc to which a pair of pistons in two banks are both connected and one stand-alone crank pin to which the remaining one piston only is connected. The common crank pins Kc are arranged at an equal phase, with a bank angle THETA set to satisfy the expression THETA = cos<-1>(1 / (2n)). The stand-alone crank pin is disposed, when the remaining piston belongs to a bank on an advance side in a crank shaft rotation direction, on a lag side in a crank shaft rotation direction with an angle of (180- THETA ) degrees away from a common crank pin Kc, the masses M of reciprocating-motion portions such as pistons in all cylinders are set equal, and the crank shaft is provided with a balance weight WB that generates a balancing force having a magnitude of kMr omega <2> in a ( alpha +180)-degree direction, when k = 2ROOT {[1 / 2 2ROOT (1-1 / 4n<2>)]<2> + (n-1 / 4n)<2>} alpha =sin<-1>[1 / 2 2ROOT (1-1 / 4n<2>) / k], where alpha : rotation-direction angle from common crank pin Kc M: mass of each reciprocating-motion portion r: crank radius omega : angular speed of crank shaft. Accordingly, an odd-cylinder V-type internal combustion engine is provided that prevents a primary vibration generation to be caused by a primary inertia force without increases in weight and size of the internal combustion engine.

Description

technical field [0001] The present invention relates to a V-type internal combustion engine with an odd number of cylinders, and more particularly to a structure for preventing primary vibration caused by primary inertial force. Background technique [0002] Conventionally, a balance mechanism such as a balance shaft has been installed in order to prevent unbalanced vibration due to inertial force occurring in reciprocating parts such as a piston of a reciprocating internal combustion engine. A balance mechanism such as a balance shaft is rotationally driven synchronously with the crankshaft by the power of the crankshaft transmitted through a transmission mechanism such as a chain or gears. Among them, the structure disclosed in Japanese Patent Application Publication No. 4-36252 is known as a balance mechanism in a V-type internal combustion engine with an odd number of cylinders. The V-shaped internal combustion engine disclosed in this gazette is a 5-cylinder internal c...

AI Technical Summary

Problems solved by technology

[0003] However, because the aforementioned prior art needs a balance mechanism in order to remove the imbalance of inertial force, and needs a space to accommodate the balance mechanism, while increasing the weight of the internal combustion engine, the internal combustion engine becomes larger, the number of parts is increased, and the number of parts is increased. Solved the problem of increased friction loss in the sliding part

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