Mechanical continuous variable valve lift mechanism

Abstract

The invention relates to a mechanical continuous variable valve lift mechanism which can lead the lift capacity of an engine valve to be changed into being closed all the way from the maximum according to the preset control value and ensure the valve timing not to be changed. The mechanism comprises a cam (101), an actuating mechanism (20) of a changeable rocker arm, the changeable rocker arm (301), a valve tappet (107), a tappet seat (108), a valve (100) and an auxiliary return spring (403); wherein the actuating mechanism (20) of the changeable rocker arm is provided with a changeable rocker arm shaft (203) which is connected with the changeable rocker arm (301), can control and change the space mechanical characteristics of the changeable rocker arm (301) and used for leading the lift capacity of the valve (100) to be continuously changed. The invention aims at thoroughly solving the problem of variable gas distribution of an internal-combustion engine puzzling the engine industry for dozens of years, omits a throttle valve of the engine, and leads continuous variable valve lift technology to be popularized to a minitype engine with less emission.

Description

technical field [0001] The invention relates to a mechanical continuously variable valve lift mechanism, which can make the valve lift of the engine vary from maximum to closed according to a preset control value and keep the valve timing constant. Background technique [0002] As we all know, because of the requirements of the best air-fuel ratio of the engine, the air volume of the cylinder must be precisely controlled for different working conditions, that is, how much air should be taken in with the throttle, otherwise the combustion will be insufficient and emission problems will occur. Technologies that can precisely control the air distribution of the engine include throttle technology and continuously variable valve lift technology. At present, the engine uses the throttle technology to control the intake air volume of the cylinder, but the throttle technology is not the technology that best meets the engine gas distribution requirements. For the throttle condition,...

AI Technical Summary

Problems solved by technology

[0005] First, the mechanism structure is complicated, the cost is expensive, and the installation is difficult, so it cannot be popularized and promoted

[0006] At present, the existing continuously variable valve lift technology in the world (including unrealized patents) is not only complex in mechanism but also has a large number of components, and requires a large space volume when installed, so it can only be installed in larger valves with medium displacement and above. On the engine, and also increase the volume of the engine cylinder head

Due to the difficulty of installation and high cost, it cannot be extended to small displacement engines

[0007] Second, the problem of the design mechanism of the double cam method

The valve timing changed in this way should be adjusted by the valve timing controller; however, the actual control of the valve timing controller in the world is still a combined switching mode based on two-level control, not multi-level intelligent control.

In some patents, the valve timing can be changed to a maximum crankshaft angle of 80 degrees, which is an angle that is difficult for the valve timing controller to achieve

In addition, when the valve timing controller rotates the camshaft, a large actuation force is required, so it is difficult for the valve timing controller to switch synchronously with the engine throttle in real time.

[0010] Third, the control accuracy of the valve lift

[0011] The reason why the control accuracy of the current continuously variable valve lift technology is insufficient or difficult to control is because the working end surface of the variable rocker arm (or swing rod, second cam) is a cam shape with large fluctuations, that is, the basis can be The variable mechanism is the double cam method

The specific manifestation is that it is very difficult to slightly change the low valve lift, and the valve opening time is extremely small at the same time when the valve lift is small, so the practical significance of setting a small valve lift becomes difficult to understand; the valve opening speed changes at medium speeds The rapidity is not smooth; when switching at high speed, the control values ​​are intensive, and the valve lift changes greatly when the control distance (or control angle) is very small, which is not easy to control

[0012] Fourth, the problem of controlling the actuation force and maintaining force

This brings great difficulties to control the actuation force when switching and control the maintenance force after switching (to maintain it without shaking)

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