Internal-combustion engines – Intake manifold – Manifold tuning – balancing or pressure regulating means
Reexamination Certificate
2000-08-04
2001-12-25
McMahon, Marguerite (Department: 3747)
Internal-combustion engines
Intake manifold
Manifold tuning, balancing or pressure regulating means
C123S184560
Reexamination Certificate
active
06332442
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an intake air duct, which serves as a passage for supplying air to an engine. More particularly, it relates to an intake air duct, in which noises are reduced when taking air in.
2. Description of the Related Art
In an intake air system of an automobile engine, there arises a problem in that noises are generated at an intake air duct when taking air in. These intake air noises are irritating to ears particularly when the engines run at low revolving speeds. Hence, a side branch and/or a resonator have been disposed in the air duct conventionally, and the noises of specific frequencies, which are calculated based on the Helmholtz resonance theory, have been reduced.
However, a large branch extends as long as about 30 cm, and a resonator of a large volume enlarges as large as 14 liters. Therefore, such a noise absorption apparatus occupies a large space in the engine room. Accordingly, there may arise a drawback in that the degree of freedom decreases in boarding the other component members.
Hence, Japanese Unexamined Utility Model Publication (KOKAI) No. 64-22, 866 discloses an orifice disposed in the intake air duct. The intake air noises are reduced by throttling the intake air passage at the orifice. When the intake air passage is throttled in such a manner, the acoustic mass enlarges, and accordingly the intake air noises of low frequencies can be reduced.
Japanese Unexamined Utility Model Publication (KOKAI) No. 3-43,576 discloses an apparatus for reducing the intake air noises. The apparatus includes two intake air tubes which are connected to an air cleaner case parallelly, two branched tubes which are branched from the respective two intake air tubes respectively, a shared resonator to which the respective branched tubes are connected altogether, and an opening-and-closing valve, which is disposed on the upstream side of the connecting portion of the branched tube of one of the intake tubes, and which opens selectively depending on the running conditions.
By the apparatus disclosed in Japanese Unexamined Utility Model Publication (KOKAI) No. 3-43,576, the opening-and-closing valve is controlled so that the number of the intake air tubes are switched from one to two, or vice versa, depending on the revolving speeds of an engine. Thus, the inlet air amount is controlled depending on the revolving speeds of the engine, and accordingly the intake air noises can be reduced.
However, in the above-mentioned method in which the intake air passage is throttled, there may arise a problem in that the inlet air amount is insufficient at the high engine revolving speeds so that the engine output decreases.
In the apparatus disclosed in Japanese Unexamined Patent Publication (KOKAI) No. 3-43,576, the opening-and-closing valve may be held between the fully closed state and the fully opened state or between the fully opened state and the fully closed state. Thus, there may be a case where the intake air tube is closed on the midway for a long period of time. In this case, although the engine is operated at low revolving speeds, the intake air noises enlarge because the acoustic mass is s mall. Accordingly, there may be a problem in that booming noises of low frequencies are heard in a passenger compartment.
Moreover, Japanese Unexamined Patent Publication (KOKAI) No. 3-43,576 discloses to use an electronic control circuit, an electromagnetic opening-and-closing valve or a diaphragm actuator, etc., for actuating the opening-and-closing valve. When these component members are used, the number of the component members increases so that the valve complicates. Moreover, it is not preferred in view of the costs.
SUMMARY Of THE INVENTION
The present invention has been developed in view of the aforementioned circumstances. It is an object of the present invention to provide an intake air duct, which reduces the intake air noises at low engine revolving speeds, which can take in a sufficient amount of air at high engine revolving speeds, which inhibits the booming noises of low frequencies from generating, and which can be made with reduced costs without using the electronic control circuit and the electromagnetic valve, etc.
An intake air duct according to the present invention can achieve the aforementioned objects, and can serve as a passage for supplying air to an engine. The present intake air duct comprises:
a first intake air passage;
a second intake air passage;
an opening-and-closing valve disposed swingably in the second intake air passage so as to open and close the second intake air passage;
an interlocking member disposed outside the first intake air passage or the second intake air passage, and swinging by interlocking with the swinging of the opening-and-closing valve; and
a coiled spring disposed swingably outside the first intake air passage or the second intake air passage, and having a swinging end brought into contact with a surface of the interlocking member, the swinging end sliding on a surface of the interlocking member as the swinging of the interlocking member;
opening the second intake air passage by the opening-and-closing valve when a first urging force, which acts onto the coiled spring while the interlocking member swings so as to interlock with the opening-and-closing valve being swung in an opening direction by a negative pressure exerted in the second intake air passage, is larger than a second urging force, which is exerted by a spring elasticity of the coiled spring; and closing the second intake air passage when the first urging force is smaller than the second urging force.
Namely, the present intake air duct can reduce the intake air noises of low frequencies at low engine revolving speeds, can take in a sufficient amount of air at high engine revolving speeds. Moreover, the present intake air duct can be made at reduced costs, because it is made without using the electronic control circuit, the electromagnetic opening-and-closing valve, the diaphragm actuator, etc.
In addition, even if water and dust may intrude into the intake air passage of the present intake air duct, and even if they deposit thereon, it is possible to inhibit the accuracy of the operations, which result from the deposited water and duct, from degrading, because the sliding portion is disposed outside the intake air passage.
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patent: 4237837 (1980-12-01), Toda et al.
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patent: 4858567 (1989-08-01), Knapp
patent: 4911111 (1990-03-01), Matsunaga et al.
patent: 5803111 (1998-09-01), Soszka
patent: 6073601 (2000-06-01), Guichard et al.
patent: 64-22866 (1987-07-01), None
patent: 3-43576 (1989-09-01), None
Fujihara Kazuo
Hirose Yoshikazu
Ishihara Hidetoshi
Kino Hitoshi
Komada Minoru
McMahon Marguerite
Pillsbury & Winthrop LLP
Toyoda Gosei Co,., Ltd.
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