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Variable valve system of internal combustion engine

a valve system and internal combustion engine technology, applied in valve arrangements, machines/engines, mechanical equipment, etc., can solve problems such as difficulty in moving back high temperature exhaust gas, and achieve the effect of increasing fuel efficiency

Inactive Publication Date: 2015-09-24
HITACHI AUTOMOTIVE SYST LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention is a variable valve system for an internal combustion engine that improves combustion by adjusting the operation angles of the intake and exhaust valves. This results in increased fuel efficiency.

Problems solved by technology

However, since, in the variable valve system of the publication, both the intake and exhaust valves are forced to take the smaller operation angle mechanically at the engine stopping, both the intake and exhaust valves inevitably show their smaller operation angle at the time of starting (or cranking) of the engine.
When, after going over the exhaust top dead center, a piston goes into an intake stroke and thus the piston starts to move down, a corresponding exhaust valve closes the exhaust port pretty soon, which however causes difficulty in moving back the high temperature exhaust gas (viz., high temperature EGR gas) from the exhaust side to a combustion chamber of the cylinder.
The difficulty tends to prevent the interior of the cylinder to be heated quickly and thus unstable combustion of air / fuel mixture in the combustion chamber is induced, which brings about the problem of exhaust emission.

Method used

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  • Variable valve system of internal combustion engine
  • Variable valve system of internal combustion engine
  • Variable valve system of internal combustion engine

Examples

Experimental program
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first embodiment

[0032]In FIG. 1, there is shown a variable valve system of a first embodiment of the present invention. The internal combustion engine to which the variable valve system is practically applied has two intake valves 1 and 1 and two exhaust valves 2 and 2 for each cylinder.

[0033]As is seen from FIG. 1, for controlling the two intake valves 1 and 1, there is employed an intake valve operation angle varying mechanism (or intake VVL) 3, and for controlling the two exhaust valves 2 and 2, there is employed an exhaust valve operation angle varying mechanism (or exhaust VVL) 4. Each mechanism 3 or 4 is constructed to stepwisely vary a valve operation angle and a valve lift amount in accordance with an operation condition of the engine.

[0034]First, the detail of the intake VVL 3 will be described.

[0035]That is, as is seen from FIGS. 1 and 2A, the intake VVL 3 comprises an intake camshaft 5 that extends in a longitudinal direction of the engine, a larger lift cam 7 integrally mounted on the i...

second embodiment

[0087]In FIGS. 6A, 6B and 7, there is shown a variable valve system of a second embodiment of the present invention.

[0088]As will become apparent as the description proceeds, the variable valve system of this second embodiment generally comprises means corresponding to the Intake VVL3 of the first embodiment, means corresponding to the Exhaust VVL4 of the first embodiment, an Intake VTC 49 that is an intake phase varying mechanism and an Exhaust VTC 50 that is an exhaust phase varying mechanism.

[0089]It is to be noted that the Intake VTC 49 and the Exhaust VTC 50 are substantially the same in construction except that respective camshafts have different phase conversion angles θI and θE.

[0090]Thus, for simplification of description, the following explanation will be directed to only the Exhaust VTC 50 and made with reference to FIGS. 6A, 6B and 7.

[0091]As is seen from FIGS. 6A and 7, the Exhaust VTC 50 is of a vane type that generally comprises a timing sprocket 51 that is driven by ...

third embodiment

[0167]In FIG. 10, there is shown a variable valve system of a third embodiment of the present invention.

[0168]As will become apparent as the description proceeds, in this third embodiment, there is employed the Exhaust VVL 4 (used in the first embodiment) that uses a hydraulic pressure for changing the valve operation mode, and the maximum lift LE2 (maximum operation angle DE2) takes the default position.

[0169]However, the intake side is different from that of the first embodiment. That is, in the third embodiment, the intake side comprises an electric type Intake VEL 80 as an intake side lift varying mechanism and an electric type Intake VTC 81 as an intake side phase varying mechanism.

[0170]As will be understood from the drawing, the Intake VEL 80 is a mechanism that continuously varies the operation angle and lift amount of the intake valves 1 and 1, which is shown in for example Japanese Laid-open Patent Application (tokkai) 2012-225287.

[0171]For ease of understanding of the thi...

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Abstract

A variable valve system of an internal combustion engine includes a first mechanism that varies an operation angle of an intake valve in accordance with a conversion actuation force applied thereto and a second mechanism that varies an operation angle of an exhaust valve in accordance with the conversion actuation force applied thereto, wherein the first and second mechanisms force mechanically the intake and exhaust valves to take smaller and larger operation angles respectively when the conversion actuation forces are not applied to the first and second mechanisms respectively.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to variable valve systems of an internal combustion engine, and more particularly to the variable valve systems of a type which is able to improve the fuel consumption of the internal combustion engine by improving a fuel combustibility at engine starting in cold air.[0003]2. Description of the Related Art[0004]In order to clarify the present invention, one related art disclosed in Jidousha Gijutsu (Automotive Technology) Vol. 43, No. 8, pages 14 to 19, published in 1989 will be briefly described before commencing description of the present invention.[0005]The variable valve system of the publication comprises an intake valve operation angle varying mechanism that varies an operating angle of intake valves of an internal combustion engine and an exhaust valve operation angle varying mechanism that varies an operating angle of exhaust valves of the engine.[0006]Each of the intake and exhaust...

Claims

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Application Information

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IPC IPC(8): F01L13/00
CPCF01L13/0031F01L1/185F01L1/267F01L1/3442F01L13/0036F01L13/0063F01L2001/0537
Inventor NAKAMURA, MAKOTO
Owner HITACHI AUTOMOTIVE SYST LTD