Double-link piston crank mechanism for internal combustion engine

Abstract

The opening (35a) on one end side of a pin-boss oil passage (35) opens to the inner-circumferential surface of a pin boss part (14) of an upper link (3), while the opening (35b) on the other end side thereof opens to the outer-circumferential surface of the pin boss part (14) of the upper link (3). A lower-link oil passage (36) has an opening (36a) on one end side thereof which opens to a lower-link (2) pin-boss-facing surface (33) facing the outer-circumferential surface of the pin boss part (14) of the upper link (3), and an opening (36b) on the other end side thereof which opens to a crank-pin-bearing surface (37). The lower-link oil passage (36) is formed so as to point, when at a prescribed crank angle, to an end edge on one end side of the upper link (3), among the end edges of the other-end-side opening (35b) of the pin-boss oil passage (35).

Description

technical field [0001] The invention relates to a multi-link piston crank mechanism of an internal combustion engine. Background technique [0002] At present, the following multi-link piston crank mechanism is known, which comprises: an upper link, one end of which is connected to the piston via a piston pin; and a lower link, which is connected to the other end of the above-mentioned upper link via an upper pin. , and is connected to the crank pin of the crankshaft; and a control link, one end of which is supported so as to be able to swing on the side of the internal combustion engine body, and the other end of which is connected to the above-mentioned lower link via a control pin. [0003] The high combustion pressure received by the piston is input from the upper pin bearing portion to the lower link via the piston pin, the upper link, and the upper pin. At the same time, in order to balance this load, a load is also generated on the crank pin bearing portion and the c...

AI Technical Summary

Problems solved by technology

[0005] However, if the lower link oil passage is not set at an appropriate position with respect to the pin seat oil passage, the burn resistance of the upper pin bearing portion will be reduced due to insufficient supply of lubricating oil

For example, when the operating range of the internal combustion engine is a high-speed rotation range, it is difficult for the lubricating oil to splash toward the opening of the lower connecting rod oil passage due to inertial force, and the pin seat oil passage is located at the bottom of the lower connecting rod oil passage when viewed in the axial direction of the crankshaft. There is a possibility that sufficient lubricating oil may not be supplied to the pin seat oil passage in the structure on the extension line of the

Images