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Engine exhaust gas temperature control systemRelated Patent Categories: Power Plants, Internal Combustion Engine With Treatment Or Handling Of Exhaust Gas, By Means Producing A Chemical Reaction Of A Component Of The Exhaust Gas, Condition Responsive Control Of Reactor Feed, Pressure, Or By-pass, Air Feed To Reactor Modulated Or Diverted By ControlEngine exhaust gas temperature control system description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060130463, Engine exhaust gas temperature control system. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority under 35 U.S.C. .sctn.119 to Japanese Patent Application No. 2004-368905. The entire disclosure of Japanese Patent Application No. 2004-368905 is hereby incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to an engine exhaust gas temperature control system configured and arranged to achieve early activation of an exhaust gas cleaning catalytic converter immediately after an engine is started. [0004] 2. Background Information [0005] Japanese Laid-Open Patent Publication No. 2002-327619 discloses a conventional engine exhaust gas temperature control system comprising a fuel injection valve configured and arranged to inject fuel directly into a combustion chamber of an engine and a secondary air supplying component (air pump) configured and arranged to supply secondary air to an exhaust passage of the engine. In such conventional engine exhaust gas temperature control system, in addition to a main fuel injection that is combusted in a main combustion in the engine, the fuel injection valve also executes a supplementary fuel injection at a timing occurring generally between the power stroke and the exhaust stroke of the engine. The fuel injected with such supplementary injection is combusted in the exhaust passage of the engine with the secondary air supplied from the secondary air supplying component, thereby causing a temperature of the exhaust gas to rise. The conventional engine exhaust gas temperature control system is configured to raise the exhaust gas temperature in order to achieve earlier activation of an exhaust gas cleaning catalytic converter provided in the exhaust passage immediately after the engine is started. [0006] In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved engine exhaust gas temperature control system. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure. SUMMARY OF THE INVENTION [0007] The conventional engine exhaust gas temperature control system disclosed in the above mentioned reference is limited to be applied to a direct fuel injection engine configured to execute a supplementary fuel injection directly into a combustion chamber at a timing occurring generally between the power stroke and the exhaust stroke. Thus, the conventional engine exhaust gas temperature control system cannot be applied to an engine configured and arranged to supply fuel into an intake passage instead of directly into a combustion chamber. Moreover, in the conventional engine exhaust gas temperature control system, the control that is required to execute the two fuel injections is complex. [0008] In an engine configured and arranged to supply the fuel into the intake passage, the temperature of the exhaust gas can be raised by increasing the amount of fuel supplied such that the air-fuel ratio of the air-fuel mixture inside the cylinder becomes rich. The rich air-fuel ratio results in a large amount of unburned fuel being discharged to the exhaust passage. By combusting this unburned fuel with secondary air supplied from a secondary air supplying component, the temperature of the exhaust gas can be raised. When this method is used to raise the exhaust gas temperature, the exhaust temperature raising effect becomes stronger the more the air-fuel ratio is richened. [0009] However, when the air-fuel ratio becomes excessively rich, this method is inhibited by such problems as rich misfiring and poor combustion stability. Also, since there is a limit to how rich the air-fuel ratio can be to achieve acceptable exhaust emissions, this method does not allow the use of an air-fuel ratio that is optimum from the standpoint of exhaust emissions. [0010] The present invention was conceived in view of these shortcomings of the conventional engine exhaust gas temperature control system. One object of the present invention is to provide an engine exhaust gas temperature control system that can be applied to an internal combustion engine configured to supply fuel to an intake passage or an intake port and can sufficiently raise the exhaust gas temperature while preventing rich misfiring by utilizing the secondary air in the exhaust passage in a highly effective manner. [0011] In order to achieve the above mentioned object and other objects of the present invention, an engine exhaust gas temperature control system is provided that comprises a combustion chamber, a fuel supplying device, a secondary air supplying device and a control unit. The combustion chamber is fluidly coupled to an intake passage and an exhaust passage with an intake valve being disposed between the intake passage and the combustion chamber and an exhaust valve being disposed between the exhaust passage and the combustion chamber. The fuel supplying device is configured and arranged to supply fuel into the intake passage. The secondary air supplying device is configured and arranged to selectively supply secondary air to the exhaust passage. The control unit is configured to execute a secondary air combustion operation in which a valve overlapping period during which the intake valve and the exhaust valve are both open is set and the fuel supplying device is controlled to inject the fuel into the intake passage so that a portion of the fuel that blows by the combustion chamber and into the exhaust passage during the valve overlapping period is combusted by the secondary air supplied by the secondary air supplying device. [0012] These and other objects, features, aspects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS [0013] Referring now to the attached drawings which form a part of this original disclosure: [0014] FIG. 1 is an overall schematic system diagram of an engine exhaust gas temperature control system in accordance with a preferred embodiment of the present invention; [0015] FIG. 2 is a flowchart executed in a control unit of the engine exhaust gas temperature control system for achieving early activation of a catalytic converter immediately after an engine is started in accordance with the preferred embodiment of the present invention; [0016] FIG. 3 is a diagram showing valve lift characteristics of an intake valve and an exhaust valve in the engine exhaust gas temperature control system in accordance with the preferred embodiment of the present invention; and [0017] FIG. 4 is a simplified diagrammatic cross sectional view of a cylinder head of an engine with the intake valve and the exhaust valve during an overlapping period illustrating a blow-by effect that occurs when a lift amount of the intake valve is small in the engine exhaust gas temperature control system in accordance with the preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0018] Selected embodiments of the present invention will now be explained with reference to the drawings. It will be apparent to those skilled in the art from this disclosure that the following description of the embodiment of the present invention is provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. [0019] FIG. 1 is an overall schematic system diagram of an engine exhaust gas temperature control system in accordance with a preferred embodiment of the present invention. As seen in FIG. 1, an engine 1 has an electronically controlled throttle valve 4 arranged in an intake passage 2 at a position near an inlet portion of an intake manifold 3. The throttle valve 4 is configured and arranged to control an intake air quantity of the engine 1. More specifically, the opening degree of the throttle valve 4 is controlled with a step motor (not shown) or the like based on a signal from an engine control unit (hereinafter called "ECU") 20. Of course, it will be apparent to those skilled in the art from this disclosure that it is also acceptable to use a mechanical throttle valve that is mechanically operated with a wire or the like connected to an accelerator pedal as the throttle valve 4. The intake passage 2 preferably includes the intake manifold 3 and a plurality of intake ports 5 (only one intake port 5 is shown in FIG. 1) that are disposed downstream portions of the intake passage 2. Continue reading about Engine exhaust gas temperature control system... Full patent description for Engine exhaust gas temperature control system Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Engine exhaust gas temperature control system patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Engine exhaust gas temperature control system or other areas of interest. ### Previous Patent Application: System for controlling the urea supply to scr catalysts Next Patent Application: Method and system for controlling exhaust gases emitted from an internal combustion engine Industry Class: Power plants ### FreshPatents.com Support Thank you for viewing the Engine exhaust gas temperature control system patent info. 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