Honda Motor Co., Ltd.

Takeru Hamakawa

Kenji Sato

Atsushi Nakajima

Yoshihiro Akiyama

Takeshi Fujii

Yoshihisa Kazui

Kuniyasu Tamura

Yoshiyuki Iida

Shigeo Okui

Naoto Kodama

Hisayuki Hashimoto

Eiji Takahashi

Teruo Kobayashi

Ichirou Ohmura

Takuma Adachi

Takenori Akiyoshi

Makoto Andou

A cooling structure for an internal combustion engine includes a spacer. The spacer is fitted inside a water jacket which is formed to surround peripheries of a plurality of cylinder bores arranged one after another on a cylinder row line of a cylinder block of the internal combustion engine. A cooling condition of the cylinder bores is controlled by regulating a flow of cooling water in the water jacket by use of the spacer. A fixing member for fixing the spacer inside the water jacket is provided on an inner wall surface of the spacer facing the cylinder bores.

Cooling structure for internal combustion engine

A spacer arranged inside a water jacket which is formed to surround peripheries of cylinder bores in a cylinder block of an internal combustion engine includes support legs extending in an up-and-down direction from a spacer main body part which partitions the water jacket into an upper and lower cooling water passages. The support legs are disposed in opposite end portions in a cylinder row line direction, where the temperatures of the cylinder bores tend to be lower. Accordingly, even if the flow of cooling water is more or less inhibited by the support legs and the cooling effect deteriorates, it is possible to prevent the temperatures of the respective cylinder bores from becoming different by suppressing the influence to a minimum.

A pulser plate mounting structure is provided in which a key groove () is formed in a mounting face () of a rotating wall portion () formed from a crank arm () and a counterweight (), a key portion () for engaging with the key groove () is formed on a pulser plate (P) that is superimposed on the mounting face (), and this pulser plate (P) is secured to the rotating wall portion () by means of a securing member (), wherein the key portion () is formed from an arched band-shaped portion () projecting in an arched shape from the pulser plate (P) on one end face side thereof and engaging with the key groove (), and a pair of connecting portions () for providing integral connection between the pulser plate (P) and opposite ends of the arched band-shaped portion (). This provides a high precision of positioning of the pulser plate relative to the crankshaft and a good productivity for the pulser plate.

Pulser plate mounting structure

A spacer fitted inside a water jacket of a cylinder block in an internal combustion engine is set so that a space formed between an inner peripheral surface of the spacer and an inner wall surface of the water jacket is smaller than a space formed between an outer peripheral surface of the spacer and an outer wall surface of the water jacket. Accordingly, even if a position of the spacer is shifted in a radial direction, the inner peripheral surface of the spacer comes into abutment on the inner wall surface of the water jacket at first. Thereby, the abutment of the outer peripheral surface of the spacer on the outer wall surface of the water jacket is prevented completely. Therefore, hitting sounds of pistons can be blocked by the space between the outer peripheral surface of the spacer and the outer wall surface of the water jacket.

A spacer covets intermediate portions of respective cylinder bores in a depth direction of a water jacket throughout the entire peripherics of the intermediate portions in the peripheral direction. Accordingly, the intermediate portion of each cylinder bore becomes higher in temperature than any other portion, and is thermally expanded. Thereby, the clearance between the cylinder bore and the corresponding piston increases. Thus, the friction decreases to improve fuel efficiency of an internal combustion engine. Furthermore, the temperature of oil lubricating the intermediate portion of the cylinder bore rises, and the viscosity decreases. Accordingly, the effect of friction reduction is enhanced more. Furthermore, upper and lower portions of the cylinder bores in a cylinder axis direction are sufficiently cooled. Therefore, the cooling performance of a top part and a skirt part of each piston, which tends to become higher in tempera lure, is secured. Accordingly, overheat can be prevented.

A height of a spacer which is arranged inside a water jacket formed to surround peripheries of cylinder bores of a cylinder block of an internal combustion engine is made to be lower by a step in an intermediate portion thereof in a cylinder row line direction. Consequently, among end-portion cylinder bores having a lower temperature and being situated at opposite end portions in the cylinder row line direction and intermediate cylinder bores being other than the end-portion cylinder bores and having a higher temperature, a cooling performance of the intermediate cylinder bores is higher than that of the end-portion cylinder bores. Therefore, all the temperatures of the respective cylinder bores can be made uniform. A similar operation effect can be obtained alternatively by making a thickness of the spacer thinner in portions facing the intermediate cylinder bores and thicker in portions facing the end-portion cylinder bores.

Growing community of inventors

Wako, Japan

Takeru Hamakawa