This application is based on and claims priority under 35 U.S.C. ยง119 to Japanese Patent Application 2008-144697, filed on Jun. 2, 2008, the entire content of which is incorporated herein by reference.
The present invention relates to a structure of an airflow control system.
Conventionally, a structure of an airflow control system where a swirl control valve is employed as a vortex control valve and a structure where a tumble control valve is employed as a vortex control valve are known. The former is described for example in JP09-228844A (hereinafter referred to as Reference 1),
According to the known structure of the airflow control system, the merging portion where the return flow passage merges with the intake passage is located upstream of the mounting position of the vortex control valve. Accordingly, the air-fuel mixture including the exhaust gas returned from the return flow passage passes through the vortex control valve. Since the exhaust gas returning to the intake passage through the return flow passage includes floating particles generated by combustion, it is highly likely that the floating particles accumulate around the vortex control valve or adhere to the vortex control valve. As a result, the vortex control valve might malfunction or the intake passage might be blocked at the mounting position of the vortex control valve.
A need thus exists for a structure of an airflow control system, which is not susceptible to the drawback mentioned above.
In light of the forgoing, a structure of an airflow control system of the present invention includes a vortex control valve located in an intake passage and generating a vortex in a combustion cylinder upon intake of air-fuel mixture for combustion, the intake passage supplying the air-fuel mixture to the combustion cylinder, and a return flow passage for returning a portion of exhaust gas generated by the combustion of the air-fuel mixture in the combustion cylinder to the intake passage, wherein a merge portion where the return flow passage merges with the intake passage is located downstream of a mounting position of the vortex control valve between the mounting position of the vortex control valve and the combustion cylinder.
The foregoing and additional features and characteristics of the present invention will become more apparent from the following detailed description considered with the reference to the accompanying drawings, wherein:
A first embodiment of the present invention will be explained with reference to the illustrations as follows.
In the first embodiment, the intake manifold 1 is made of synthetic resin. The intake manifold 1 is structured to include an intake passage that passes through an air filter and through a fuel injector, and that is divided into four intake passages each of which leads to a corresponding combustion cylinder 3A.
The cylinder head 3 is made of metal and includes the four combustion cylinders 3A. In each of the combustion cylinders 3A, a cycle of intake, compression, fire, and exhaust takes place repeatedly to generate a driving force to rotate a crankshaft. The intake manifold 1 is connected to the cylinder head 3, on a side on which the intake passage 6 is located, so as to communicate with the cylinder head 3 via the airflow control system 2. In the meantime, the exhaust manifold 4 is connected to the cylinder head 3, on a side on which the exhaust passage 7 is located, so as to communicate with the cylinder head 3.
The exhaust gas recirculation system 5 is structured to include the return flow passage 8 and a CPU controls the recirculation of exhaust gas by regulating a flow of the exhaust gas returned to the return flow passage 8. A merging portion 9 where the return flow passage 8 merges with the intake passage 6 is provided on the airflow control system 2.
As shown in
As shown in
The vortex control valve 10 of the first embodiment is, for example, a tumble (longitudinal vortex) control valve. As shown in
In the meantime, as shown in
According to the structure of the airflow control system of the first embodiment, as shown in
Second and third embodiments of the present invention will be explained as follows.
The structure of the airflow control system of the first embodiment is applied not only to the engine structure previously described but it may also be applied to other types of internal combustion engines operating on diesel fuel or other fuels, or to engines having any other number of cylinders. The vortex control valve 10 may have other shapes, configurations, or structures than those described in the first embodiment. A swirl control valve may also be applied instead of the tumble control valve. A position or shape of the wide U-shaped notch 12 formed on the valve vane 10B may be appropriately modified. In essence, the vortex control valve 10 needs to be located upstream of the merging portion 9 where the return flow passage 8 merges with the intake passage 6. Also, it is ideal that the wide U-shaped notch 12 is located one portion of the intake passage 6 in the radial direction thereof and the merging portions 9 is located on another portion of the passage 6, rather than they are located on the same portion. In the first embodiment, the airflow control system 2 includes the first and second plate members 2A, 2B, and the groove M serving as the return flow passage 8 is formed on the second plate member 2B. However, the airflow control system 2 may include other structures where, for example, the groove M is formed on the first plate member 2A as shown in
The reference numbers used in the embodiments are for convenience of referencing to the drawings, and the present invention is not limited to the structures shown in the drawings. The present invention may be embodied in various forms without departing from the scope of the invention.
Due to the above-described structure, the merging portion 9 where the return flow passage 8 merges with the intake passage 6 is located downstream of the mounting position of the vortex control valve 10 between the mounting position of the vortex control valve 10 and the combustion cylinder 3A. Therefore, the exhaust gas discharged from the return flow passage 8 to the intake passage 6 is delivered to each of the combustion cylinders 3A via downstream of the vortex control valve 10 without passing therethrough. Consequently, the floating particles in the exhaust gas are prevented from accumulating in the mounting position of the vortex control valve 10 or adhering to the vortex control valve 10. As a result, the environmental conditions of the mounting position of the vortex control valve 10 are maintained normal, which prevents the vortex control valve 10 from malfunctioning due to the floating particles and preventing the intake passage 6 from being blocked by the floating particles at the mounting position of the vortex control valve 10.
According to the first embodiment, the vortex control valve 10 includes the wide U-shaped notch 12 for inducing the air-fuel mixture to one portion of the intake passage 6 in the radial direction of the intake passage 6 under the condition that the flow of the air-fuel mixture is throttled and the merge portion 9 is formed on a wall of the intake passage 6 so as to open in a direction of another portion of the passage 6 different from the one portion.
Consequently, the flow of the air-fuel mixture that has the vortex generation enhancing effect and passes through the vortex control valve 10, and the return flow of the exhaust gas discharged from the merging portion 9 located downstream of the vortex control valve 10 are divided in the radial direction of the intake passage 6, and that the mutual interference is prevented.
According to the first embodiment, the structure of the airflow control system includes the first plate member 2A and the second plate member 2B assembled on each other and located between the cylinder head 3 and the intake manifold 1, wherein the vortex control valve 10, the return flow passage 8 and the merge portion 9 are provided between the first plate member 2A and the second plate member 2B.
By providing the vortex control valve 10, the return flow passage 8 and the merging portion 9 on the first and second plate members 2A, 2B, space-saving and the assemble efficiency are improved compared to a structure where a vortex control valve, a return flow passage and a merging portion are individually provided.
According to the first embodiment, the first plate member 2A and the second plate member 2B respectively include the through hole H for forming the intake passage 6.
According to the third embodiment, the structure of the airflow control system includes the plate member 2A located between the cylinder head 3 and the intake manifold 1, wherein the vortex control valve 10, the return flow passage 8 and the merge portion 9 are provided on the plate member 2A.
The principles, preferred embodiments and modes of operation of the present invention have been described in the foregoing specification. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. Variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such variations, changes and equivalents which fall within the spirit and scope of the present invention as defined in the claims, be embraced thereby.
Number | Date | Country | Kind |
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2008-144697 | Jun 2008 | JP | national |