Combined piston

Abstract

The invention discloses a combined piston. The combined piston comprises a piston upper part, a piston lower part and a connecting piece; an annular inner cold oil channel is formed in the piston upper part; at least one pair of connecting holes which are centrally symmetrical about a ring center are arranged at the bottom of the annular inner cold oil channel; and the piston lower part and the piston upper part are in fit pressing and are firmly connected with the connecting holes through the connecting piece. The combined piston has the advantages of low manufacturing cost, easiness in formation, high reliability, high connecting strength and capability of reducing weight.

Description

technical field [0001] The invention mainly relates to the technical field of internal combustion engines, in particular to a combined piston. Background technique [0002] The emission upgrade of the internal combustion engine is a continuous requirement for the internal combustion engine industry, and the piston is one of the key components to promote the emission upgrade. The steel structure piston replaces the aluminum structure piston is an important means to meet the emission requirements. The all-steel integral structure piston adopts integral forging or casting Forming or separate forging billet welding forming, the weight of the all-steel integral structure piston is heavy, and the forming process is difficult, which is not conducive to reducing the motion load of the piston connecting rod group. In order to reduce the difficulty of forming process and the weight of the piston, the steel top aluminum The combined structure of the skirt reduces the weight of the pist...

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Problems solved by technology

[0002] The emission upgrade of the internal combustion engine is a continuous requirement for the internal combustion engine industry, and the piston is one of the key components to promote the emission upgrade. The steel structure piston replaces the aluminum structure piston is an important means to meet the emission requirements. The all-steel integral structure piston adopts integral forging or casting Forming or separate forging billet welding forming, the weight of the all-steel integral structure piston is heavy, and the forming process is difficult, which is not conducive to reducing the motion load of the piston connecting rod group. In order to reduce the difficulty of forming process and the weight of the piston, the steel top aluminum The combined structure of the skirt reduces the weight of the piston while meeting the heat load requirements of the head, which provides a good solution to the above problems, such as: CN201510040273.3 Steel piston and its processing method based on laser welding forming inner cooling oil cavity, It better solves the forming problem of the cooling oil cavity in the piston; CN201220646167.1 The double cooling oil cavity welded integral forged steel internal combustion engine piston provides a friction welded double oil cavity structure piston with an all-steel structure; CN200820159361.0 a The combined piston structure can effectively reduce the weight of the piston while satisfying the high explosion pressure of the internal combustion engine, and reduce the operating load of the piston connecting rod group; CN02274796.6 The improvement of the steel top aluminum skirt piston for 280 / 285 series locomotive diesel engines provides a combination of multiple Bolted combined piston

[0003] The bolt-connected combined structure piston provides a good idea and method for reducing the heat load on the upper part of the piston and the weight of the piston. However, the technical solution has the following problems: First, the steel structure support and connection part of the upper part of the piston are thick and heavy , which increases the motion load; second, the annular cooling oil passage on the upper part of the piston is an open structure, and the piston ring groove is easily deformed by force during the working stroke, which increases the wear of the ring groove; third, the connecting parts bear repeated high temperature and high pressure loads, and the bolts are easy to Stress relaxation and connection failure occur; Fourth, the connection structure of the inner and outer oil chambers is not conducive to the cooling of the head of the V-shaped structure engine piston, which reduces the cooling effect

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