A variable valve system for two-stroke and four-stroke engines

Abstract

The invention provides a variable air valve system of a two-four stroke engine. The system comprises a cam shaft, a first cam, a second cam, a hydraulic cylinder, an air valve and a cam phase positionadjusting mechanism; the first cam and the second cam sleeve the cam shaft side by side, and at least one cam is movable; a first hydraulic cavity and a second hydraulic cavity are formed in the topof the hydraulic cylinder side by side, and a first plunger piston and a second plunger piston which can slide up and down are respectively arranged in the first hydraulic cavity and the second hydraulic cavity; the top end of the air valve is fixedly connected with a piston, and the piston can slide along the space of the inner wall of the hydraulic cylinder; by controlling the cam phase positionadjusting mechanism, the first cam and the second cam can at least achieve two states that the cam phase position portions of the first cam and the second cam overlap, and the cam phase positions aresymmetrically distributed about the axis of the cam shaft, and variable 2 / 4 stroke is finally achieved. According to the system, it is not necessary to operate a control mechanism in each work circulation, in the working condition that the stroke needs to be changed, the control system can be adjusted, the control is simple, and the system is beneficial for engineering application of the variableair valve technology.

Description

technical field [0001] The invention belongs to the technical field of engines, in particular to a variable valve system of a two-stroke or four-stroke engine. Background technique [0002] The internal combustion engine is still the prime mover with the highest thermal efficiency and the largest power per unit volume and unit weight. It is widely used. However, with the gradual shortage of energy in the world and the continuous deterioration of environmental resources, we need internal combustion engines to meet stricter emission regulations and economic indicators. . Traditional internal combustion engines use fixed-profile camshafts to drive valves, which makes the emissions and fuel consumption of internal combustion engines not optimal at all operating points. Therefore, most new internal combustion engines use variable valve technology to control emissions and reduce fuel consumption. [0003] At present, variable valve technology is mainly divided into camshaft-based...

AI Technical Summary

Problems solved by technology

Compared with the disadvantages of high energy consumption of electromagnetic drive, low and unstable response speed of electric drive, and complex motor-driven system, the camless gas distribution technology of electro-hydraulic drive has relatively simple structure and fast response speed

However, it also has unavoidable disadvantages: the flow rate of the hydraulic system is not enough at high speed, the valve reaches the maximum lift and the seat is fast, and the impact force is large.

Therefore, it is mainly used in low-speed engines such as diesel engines. In addition, it is necessary to use expensive electro-hydraulic servo systems and relatively complex control technologies to accurately control the valve stroke to avoid seating impact, which greatly increases the engine. cost

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