Internal-combustion engines – Charge forming device – Exhaust gas used with the combustible mixture
Reexamination Certificate
1999-05-24
2001-01-16
Yuen, Henry C. (Department: 3747)
Internal-combustion engines
Charge forming device
Exhaust gas used with the combustible mixture
C123S184610
Reexamination Certificate
active
06173701
ABSTRACT:
The contents of Patent Applications Nos. 8-245793 and 8-245794, with a filing date of Sep. 18, 1996 in Japan, are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to emission control systems for an internal combustion engine, and particularly to an exhaust gas recirculation (EGR) system of the engine. More specifically, the present invention relates to an improvement in connecting an EGR valve or an EGR pipe to a plastic intake manifold of an internal combustion engine.
2. Description of the Prior Art
Hitherto, in motor vehicles powered by an internal combustion engine, an exhaust gas recirculation (EGR) system has been commonly installed for reducing NOx emissions produced by the engine. As is known, the EGR system is designed to recirculate a metered amount of exhaust gas into the air-fuel mixture in the combustion chambers to reduce the temperature in the combustion chambers and thus NOx emissions. In the EGR systems, an EGR valve is installed in an EGR passage for regulating the amount of EGR. Usually, the EGR valve is connected to an intake manifold of the engine. Under operation of the EGR system, the EGR valve which is constructed of a metal is highly heated by absorbing heat of the recirculating exhaust gas.
Thus, if the intake manifold is constructed of a plastic (viz., glass fiber-reinforced plastic) for reducing the weight of the engine system or for other reasons, it is necessary to take any measure for protecting the plastic intake manifold from the heat of the EGR valve.
Hitherto, various measures have been proposed and put into practical use for protection of the plastic intake manifold from the heat of the EGR valve, some of which are shown in Japanese Patent First Provisional Publications 5-256217 and 6-101587 and Japanese Utility Model First Provisional Publication 63-164554. In the Publication 5-256217, the EGR valve is mounted to the plastic intake manifold through a mounting bracket of corrugated stainless steel plate. In the Publication 6-101587, the EGR valve is connected to the plastic intake manifold with an interposal of a heat insulator therebetween, first bolts are used to secure the heat insulator to the manifold and second bolts are used to secure the valve to the heat insulator. In the publication 63-164554, a junction portion between the EGR valve and the plastic intake manifold is formed with an annular groove through which a coolant flows for cooling the junction portion.
In addition to the above-mentioned measures, a measure for protection of the plastic intake manifold from the heat of exhaust gas is described in Japanese Utility Model First Provisional Publication 1-102465. In this measure, a fresh air from an air cleaner is fed into an EGR pipe to reduce the temperature of the EGR gas led into the plastic intake manifold. Furthermore, for suppressing or minimizing direct contact of the highly heated exhaust gas with an inner wall of the plastic intake manifold, a leading end of the EGR pipe is projected into the interior of the intake manifold through a pipe passing opening formed in the same.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an exhaust gas recirculation system of an internal combustion engine, which is provided in view of the disclosure of the above-mentioned publications.
According to a first aspect of the present invention, there is provided an exhaust gas recirculation system for use with an internal combustion engine having a plastic intake passage. The system comprises a connecting base formed on the plastic intake passage, the connecting base having an exhaust gas inlet hole connected with the interior of the intake passage; an exhaust gas recirculation valve through which a metered amount of exhaust gas produced by the engine is fed back to the interior of the plastic intake passage; and a cooling device arranged between the connecting base and the exhaust gas recirculation valve, the cooling device including mutually separated first and second passages, the first passage connecting an outlet opening of the exhaust gas recirculation valve to the exhaust gas inlet hole of said connecting base, the second passage being shaped to surround the first passage and adapted to flow therein a coolant. The first passage of the cooling device includes a pipe portion which penetrates through the exhaust gas inlet hole keeping a given space between an outer wall of the pipe portion and an inner wall of the exhaust gas inlet hole.
According to a second aspect of the present invention, there is provided an exhaust gas recirculation system for use with an internal combustion engine having a plastic intake passage. The system includes a connecting base formed on the plastic intake passage, the connecting base having an exhaust gas inlet hole connected with the interior of the intake passage; an exhaust gas recirculation valve through which a metered amount of exhaust gas produced by the engine is fed back to the interior of the plastic intake passage; and an exhaust gas recirculation pipe having first and second end portions, the first end portion penetrating through the exhaust gas inlet hole and the second end portion being connected to an outlet opening of the exhaust gas recirculation valve. An opening defined by an inner end of the exhaust gas inlet hole is larger than that defined by the other portion of the exhaust gas inlet hole.
According to a third aspect of the present invention, there is provided a cooling device for use in an exhaust gas recirculation system. The device comprises a front housing member; a rear housing member; a seal member; and bolts for coupling the front and rear housing members having the seal member interposed therebetween thereby to constitute a housing unit. The housing unit includes mutually separated first and second passages, the first passage being adapted to pass therethrough exhaust gas for the exhaust gas recirculation, the second passage being shaped to surround the first passage and adapted to flow therethrough a coolant.
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Anonymous, “Exhaust Gas Recirculation Device”, Research Disclosure 327113, Jul. 1991/549.
Castro Arnold
McDermott & Will & Emery
Nissan Motor Co,. Ltd.
Yuen Henry C.
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