A hydraulic variable valve lift mechanism for a valveless engine

Abstract

The invention provides a hydraulic variable valve lift mechanism for an engine without a valve spring, which includes a camshaft, a stator and a valve; the camshaft is sleeved on the stator and can rotate around the stator; a piston and a piston spring are arranged inside the stator , the piston spring provides upward spring force to the piston; the lower end of the piston rod is fixedly connected to the roller, and the lower end of the roller is fixedly connected to the valve; there is a guide groove matching the roller between the inner wall of the camshaft and the outer wall of the stator, and the guide groove is in the shape of a cam; through the control piston The hydraulic pressure at the upper end can change the moving distance of the piston relative to the stator, so as to realize the variable maximum lift of the valve. The invention cancels the valve spring, can realize higher inflation efficiency, and at the same time, the control is simple, which is beneficial to the engineering application of the variable valve technology.

Description

technical field [0001] The invention belongs to the technical field of engine variable valve hydraulic actuators, in particular to a hydraulic variable valve lift mechanism for engines without valve springs. 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. 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 divide...

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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