Two-stage variable compression ratio system of gasoline engine and control method thereof

A control method and compression ratio technology, applied in mechanical equipment, engine components, machines/engines, etc., can solve the problems of high cost and impracticality, and achieve the effect of high power density, rapid change, and avoidance of knocking

Inactive Publication Date: 2010-04-28
TSINGHUA UNIV
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  • Abstract
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Problems solved by technology

However, the method of continuously variable compression ratio is not practical for vehicle engines at prese

Method used

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  • Two-stage variable compression ratio system of gasoline engine and control method thereof
  • Two-stage variable compression ratio system of gasoline engine and control method thereof
  • Two-stage variable compression ratio system of gasoline engine and control method thereof

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Embodiment Construction

[0024] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0025] The gasoline engine two-stage variable compression ratio system of the present embodiment, such as figure 1 As shown, on the two overhead camshafts corresponding to the intake valve and exhaust valve of the engine, the intake valve 10 and the exhaust valve 20 of each cylinder are respectively provided with a large cam and a small cam; 10 is provided with an intake valve cam profile switching mechanism 11 for switching the intake valve large cam 13 and intake valve small cam 12 corresponding to the intake valve 10; The valve cam profile switching mechanism 21 is used for switching the large exhaust valve cam 23 and the small exhaust valve cam 22 corresponding to the exhaust valve 20 . figure 2 It is a schematic diagram of the above four kinds of cam lift curves.

[0026] The geometric compression ratio of the gasoline engine o...

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Abstract

The invention relates to a two-stage variable compression ratio system of a gasoline engine and a control method thereof. On two overhead camshafts corresponding to an intake valve and an exhaust valve of the engine, a big cam and a small cam, which correspond to the intake valve and the exhaust valve of each cylinder are respectively arranged; an intake valve cam profile switching mechanism is arranged on the intake valve of each cylinder and is used for switching the big cam and the small cam of the intake valve, which correspond to the intake valve; and an exhaust valve cam profile switching mechanism is arranged on the exhaust valve of each cylinder and is used for switching the big cam and the small cam of the exhaust valve, which correspond to the exhaust valve. The system and the method have the advantages of quickly changing the compression ratio, realizing the switching between SI and HCCI combustion modes in an engine cycle, obtaining low oil consumption by adopting a high compression ratio when the engine has a medium or low load, and obtaining a high-power density by adopting a low compression ratio to avoid detonation when the engine has a high load.

Description

technical field [0001] The invention relates to the technical field of internal combustion engines, in particular to a gasoline engine adopting HCCI / SI mixed combustion mode, that is, a homogeneous mixed gas compression ignition combustion (HCCI) mode with a high compression ratio is adopted at medium and small loads to achieve high efficiency and low pollution, and low compression is adopted at large loads Compared with the spark ignition (SI) combustion mode, high power density is obtained without knocking. Background technique [0002] Gasoline engines have high fuel consumption in small and medium loads, which is 20% to 30% higher than diesel engines; while in heavy loads, they are prone to knocking, which limits power output. In order to solve the problem of poor fuel consumption of gasoline engines in small and medium loads, it is necessary to increase the compression ratio; to solve the problem of easy knocking of gasoline engines in heavy loads, it is necessary to re...

Claims

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Application Information

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IPC IPC(8): F01L13/08
Inventor 王志王建昕
Owner TSINGHUA UNIV
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