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A Design Method of Flexible Valve Cam Curve

A valve cam, cam curve technology, applied in the direction of calculation, special data processing applications, instruments, etc., can solve the problems of positive acceleration peak value or positive and negative acceleration peak value increase, cam time face value reduction and other problems

Active Publication Date: 2016-12-28
BEIJING INSTITUTE OF TECHNOLOGYGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Therefore, to increase the time face value of the trapezoidal acceleration cam, it can be realized by reducing the duration of the positive acceleration segment or the negative acceleration segment, but this will cause the increase of the positive acceleration peak value or the positive and negative acceleration peak values; The positive and negative acceleration peaks can be achieved by increasing the duration of the positive and negative acceleration segments, but this will also reduce the time face value of the cam

Method used

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  • A Design Method of Flexible Valve Cam Curve
  • A Design Method of Flexible Valve Cam Curve
  • A Design Method of Flexible Valve Cam Curve

Examples

Experimental program
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Embodiment

[0081] The original acceleration curve of the follower matched with the valve cam of a certain diesel engine is as follows: image 3 As shown, its boundary conditions are

[0082] V(0)=0.17, V(1)=0.0, A(0)=0.5, A(1)=0.0

[0083] Consider the relationship between the acceleration peak value, the time surface value and the length of each acceleration segment, and the limit on the jerk value (generally, the jerk value is required to be less than 80), refer to the acceleration peak value of the original acceleration curve and the length of each acceleration segment, and determine its driven The length of each segment of the piece speed curve is

[0084] T 1 =0.09, T 2 =0.3, T 3 =0.45, T 4 =0.84, T 5 =0.92

[0085] The initial displacement curve is obtained by formula (6), and then 20 model value points are evenly taken on the displacement curve, and the 5th degree B-spline curve fitting program is used to fit the curve to obtain a 19-segment 5th degree B-spline curve. The ...

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Abstract

The invention discloses a design method of a flexible air distribution cam curve. The cam curve is represented by a driven member displacement curve. The design method comprises the steps that according to relation among lengths of various acceleration sections, time-area values and positive and negative acceleration peaks in a trapezoidal acceleration curve of a driven member matched with a cam, and requirements of a designed engine air distribution mechanism on the acceleration peaks, the time-area values and jerk values of the driven member, lengths of the various acceleration sections are determined; an ideal trapezoidal acceleration curve is obtained; a driven member displacement curve is obtained by integration; a plurality of points are taken from the displacement curve to serve as a data point set; and the final driven member displacement curve, namely the cam curve, is obtained by fitting a quintic B splined curve. The cam curve obtained by the design method has the characteristics of high time-area value, low positive and negative acceleration peaks and higher-order continuation; requirements of an air distribution cam mechanism on the air change performance and the dynamic performance can be met better; and the cam curve is the flexible air distribution cam curve, and has the characteristics that the B splined curve is high in adaptability, and facilitates local modification.

Description

technical field [0001] The invention relates to a design method of a cam displacement curve, in particular to a design method of a flexible valve cam displacement curve, and belongs to the technical field of engine design. Background technique [0002] The four-stroke engine widely adopts the valve-cam valve mechanism, that is, the opening and closing of the valve is controlled by the cam to control its intake and exhaust. The quality of the valve mechanism design has an important impact on the performance of the engine. Since the cam-type valve mechanism realizes gas distribution by driving the valve with the cam, the performance of the valve mechanism depends to a large extent on the design of the cam curve. [0003] Generally speaking, the valve train should have good ventilation performance on the one hand, which can be achieved by increasing the time-area value (referred to as the face value) of the lift curve of the follower (for the follower, the lift The value is it...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06F19/00F01L1/06
Inventor 覃文洁陈友明
Owner BEIJING INSTITUTE OF TECHNOLOGYGY
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