US 6,684,830 B2 · Variable valve timing engine

Abstract

An EGR passage 8 that recirculates exhaust gases in an exhaust pipe 5 of an engine 1 to an intake system by negative intake-gas pressure is provided. An intake cam 24 that opens and closes an intake valve 6 is provided so that a phase angle of the intake cam 24 may be adjusted through a VTC 27 (phase angle adjustment means). The phase angle of the intake cam 24 is adjusted in accordance with increase or decrease of a flow rate of recirculation of exhaust gases, thus restricting occurrence of NOx.

Drawings

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Drawings

Claims11

Dependent claims

A variable valve timing engine comprising:

an EGR passage through which exhaust gases are recirculated from an exhaust system to an intake system;
a phase angle adjustment means that adjusts a phase angle between an exhaust cam for opening/closing an exhaust valve and an intake cam for opening/closing an intake valve, and adjusts overlap or time during which both intake and exhaust valves are open;
and
a phase angle adjustment control means that controls the phase angle adjustment means in accordance with a flow rate of recirculation of the exhaust gases in the EGR passage,
wherein the phase angle adjustment control means restricts an phase angle adjustment amount by the phase angle adjustment means if the overlap based upon the flow rate of recirculation of the exhaust gases in the EGR passage is larger than the overlap based upon a driving state of the engine.

2 more elements

Dependencies are inferred from the claim text.

Description8,195 words

Summary2,213 words

#This invention relates to a variable valve timing engine including an exhaust gas recirculation device (hereinafter referred to as “EGR device”) that recirculates part of exhaust gases back to a combustion chamber to reduce NOx emissions.

#A conventional EGR device, for example, as disclosed in Japanese Laid-Open Patent Application, Publication No. 11-125126, A, includes an exhaust gas recirculation passage (hereinafter referred to as “EGR passage”) and an exhaust gas recirculation valve (hereinafter referred to as “EGR valve”). The EGR passage is provided to connect an intake passage and an exhaust passage with each other. The EGR valve is provided at a junction of an upstream end of the EGR passage and the exhaust passage to open and close the EGR passage. The EGR valve may open and close the EGR passage between a wide-open state and a tightly closed-off state inclusive to control a recirculation flow rate of exhaust gases flowing from the exhaust passage to the intake passage. The EGR valve opens, closes, or throttles based upon loads on the engine, engine speeds, temperature of cooling water, or the like, so as to recirculate exhaust gases at a controlled flow rate according to a varying driving state to the combustion chamber of the engine. A variable valve timing engine including a phase angle adjustment means that adjusts a phase angle between an exhaust cam for opening/closing an exhaust valve and an intake cam for opening/closing an intake valve is also known in the art.

#Recirculation of part of exhaust gases through the EGR passage to the combustion chamber of the engine may advantageously restrict a steep increase in combustion speed and combustion heat, lowers combustion temperature, and thus reduces NOx emissions. Further, reduced pumping loss due to the recirculation may contribute to increased fuel efficiency.

Brief description of the drawings11 figures

#FIG. 1 is a system configuration chart of a four-stroke-cycle engine including an EGR passage and a variable valve timing control (VTC) as a phase angle adjustment means according to a variable valve timing engine as one embodiment of the present invention.

#FIG. 2 is a schematic illustration of a drive system and a valve system of a variable valve timing engine according to the present invention.

#FIG. 3 is a cross-sectional view of an internal structure of a variable valve timing control according to the present invention with a principal part illustrated in detail.

Detailed description5,617 words

#One embodiment of the present invention will be described with reference to FIGS. 1 through 10.

#FIG. 1 depicts a four-stroke-cycle engine system according to the present invention; FIG. 2 depicts structures of a drive system and valve system of the same engine.

#In these drawings, denoted by 1 is an engine, denoted by 2 is a cylinder block, denoted by 3 is a cylinder head, denoted by 4 is an intake pipe (including an intake port) that defines an intake passage, and denoted by 5 is an exhaust pipe (including an exhaust port) that defines an exhaust passage.

Facts

Application

10/101,700Filed 21 Mar 2002

Priority

JP 2001-08394523 Mar 2001

Published

US 2002/0134333 A126 Sep 2002

Granted

3 Feb 2004

Term ended

21 Mar 2022

Estimated · how

20 years from earliest known nonprovisional domestic filing plus recorded patent term adjustment. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination.

Classification3 codes

F01L 1/34
Valve-gear or valve arrangements, e.g. lift-valve gear: characterised by the provision of means for changing the timing of the valves without…
F01L 2001/34469
Locking means between driving and driven members: lock movement parallel to camshaft axis
F01L
Cyclically operating valves for machines or engines

Variable valve timing engine

Life of this patent

Variable valve timing engine

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims11

Description8,195 words

Drawings

Classification3 codes

Life of this patent

Description8,195 words