Intake system structure of power unit

Abstract

This intake system structure of a power unit (5), which is mounted to a vehicle (1), and in which an internal combustion engine (2) and a power transmission 3 are integrated with each other, an air cleaner (50) is provided at a position away from a cylinder part (44) of the internal combustion engine (2), a throttle body (52) is disposed at a position close to the cylinder part, and the air cleaner and the throttle body are connected to each other by a connecting tube (51), wherein a regulating member (54) around the axis of an intake passage (52a) regulates the throttle body (52) in a position in the rotating direction around the axis with respect to the cylinder part, the throttle body is assembled to the cylinder part through an inlet manifold (53) and supported integrally, and in the throttle body, a connecting cylindrical part (60) to the connecting tube is provided with a positioning part (61) for positioning the connecting tube in the rotating direction.

Description

technical field [0001] The present invention relates to an air intake system structure of a power unit equipped with an internal combustion engine mounted on a vehicle, particularly a small vehicle. Background technique [0002] At present, in the air intake system of a power unit integrated with an internal combustion engine and a power transmission device mounted on a vehicle, especially a small vehicle, as shown in the following patent document 1, the throttle valve area is provided with the internal combustion engine and the air filter. Between the cleaners, the throttle area is connected to the air filter through a connecting pipe. In addition, the downstream end of the connecting pipe is fixedly supported by fastening the periphery of the upstream inlet portion in which the throttle valve region is fitted in the downstream end of the connecting pipe with a fastening band. [0003] Patent Document 1: Japanese Unexamined Patent Publication No. 2006-291777 ( figure 2 , ...

AI Technical Summary

Problems solved by technology

[0004] However, as shown in the aforementioned Patent Document 1, for example, in a power unit in which the air cleaner is disposed at a position separated from the cylinder portion of the internal combustion engine and the throttle region is disposed at a position close to the cylinder portion, the connecting pipe is generally relatively long. Components that are prone to deviations in the rotational position around the pipe axis in the fastening portion during installation

If tightening is performed when there is deviation in alignment in the direction of rotation, shape deformation, etc., may occur due to torsional stress.

[0005] In addition, in order to accurately perform such alignment, a complicated structure and complicated connection work are required.

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