JP3660291B2 - Intake device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an intake device for an internal combustion engine having a blow-by gas discharge port upstream of a throttle valve in a downflow type intake passage.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a structure in which an intake passage is connected to an oil pan, a cylinder head, and the like to recirculate blow-by gas is well known. This blow-by gas recirculation structure is applied to an internal combustion engine having a downflow type intake passage that hangs down from upstream to downstream of intake air, and the blow-by gas discharge port to the intake passage is connected upstream of the throttle body, that is, above In other words, the oil droplets contained in the blow-by gas may travel along the inner wall surface of the intake passage and adhere to the throttle valve in the throttle body, in particular its opening / closing shaft and bearings, resulting in a dull operation. is there.
[0003]
For example, in Japanese Patent Laid-Open No. 10-77913, a blow-by gas passage is formed in an annular shape along the outer periphery of the main intake passage, and this blow-by gas passage is formed to spirally spiral in the flow direction of the main intake passage. A different structure is disclosed. This publication discloses a structure in which a blow-by gas discharge port is formed on the downstream side of the throttle valve, that is, the blow-by gas does not pass through the throttle valve, so that the throttle valve is not contaminated.
[0004]
[Problems to be solved by the invention]
However, since the throttle body is usually provided in the vicinity of the surge tank of the intake manifold, the structure in which the blow-by gas discharge port is provided between the surge tank and the throttle body is limited in layout because the discharge port position is limited. There was a problem that the degree decreased. Further, in the structure disclosed in the above publication, it is necessary to integrally form an annular recirculation gas passage on the outer periphery of the main intake passage, which makes the formation complicated and further reduces the degree of layout freedom.
[0005]
The present invention has been devised to solve the above-described problems of the prior art, and in an intake device for an internal combustion engine having a blow-by gas recirculation structure and a downflow type intake passage, the degree of freedom in layout is increased. An object of the present invention is to easily prevent fouling around the opening and closing shaft of a throttle valve due to blowby gas oil droplets and the like without lowering.
[0006]
[Means for Solving the Problems]
To achieve the above object, the present invention provides a suction system for an internal combustion engine having a discharge opening 8a of the blow-by gas on the upstream side of the in throttle valve 5 in an intake passage of the down flow type, the intake of the intake passage An annular recess 10 that gradually increases in diameter from above to below is formed between the throttle valve 5 and the blow-by gas discharge port 8a in the passage wall, and the throttle valve is opened at the lower end of the annular recess. An annular surface having an upper surface that is inclined downward on the side (position A) corresponding to the side that moves downward when the throttle valve is opened so as to guide the droplet toward the side that moves downward (position C) when the valve is opened. The step portion 11 is formed (configuration of claim 1) . As a result, a droplet such as an oil droplet with a simple structure is guided to the portion (C) that does not interfere with the opening / closing shaft 5a of the throttle valve 5 and flows downward as the throttle valve 5 opens. In particular, by forming the annular recess 10 that gradually increases in diameter from the upper side toward the lower side in the intake passage and forming the annular step portion 11 at the lower end thereof, disturbance of the intake air flow is prevented. In addition, the annular step portion 11 is integrally formed with the air flow tube 6 in the air flow tube 6 that connects the air cleaner 7 and the throttle body including the throttle valve 5 (configuration of claim 2) . By simply devising the shape of the intake passage wall, a guide structure can be realized and manufacturing becomes easy.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0008]
FIG. 1 is a front perspective view of an in-line four-cylinder engine as an internal combustion engine to which the present invention is applied, and FIG. 2 is a side sectional view around a throttle valve in an intake passage of the engine of FIG. At the front of the engine, there are an intake manifold 2 connected to an intake port provided in the cylinder head 1, and a surge tank 3 connected to the intake upstream end of the intake manifold 2 and disposed at the lower part of the intake manifold 2. And a throttle body 4 having a throttle valve 5 therein and one end connected to the upper end of the throttle body 4, that is, the intake upstream end. The other end of the air flow tube 6 is connected to the air cleaner 7. The air flow tube 6 extends substantially horizontally from the air cleaner 7, hangs downward at an intermediate portion, and reaches the throttle body 4. A portion 6a that hangs downward from the airflow tube 6 and the throttle body 4 form a downflow type intake passage. The other end of a breather tube 8 having one end connected to a breather tank (not shown) is connected to the vicinity of the intake outlet of the air cleaner 7 to recirculate the blowby gas, and a blowby gas discharge port 8a opens into the intake passage ( FIG. 4). The air cleaner 7 is connected to an outside air inlet (not shown) via another air flow tube 9.
[0009]
As shown well in FIG. 3 viewed along the line III-III in FIG. 2, the intake passage is located on the inner wall of the portion 6a that hangs downward in the air flow tube 6, that is, the position above the throttle body 4 in the intake passage. Gradually increases in diameter, and an annular recess 10 is formed. An annular step 11 as a droplet guide structure is formed at the lower end of the annular recess 10. The upper surface of the annular step portion 11 is inclined obliquely downward from the opposite position B toward the position A corresponding to the upper position C where the throttle valve 5 moves downward when the valve is opened (Claim 1). . The annular step portion 11 is formed integrally with the air flow tube 6 (claim 2) .
[0010]
With this structure, as shown in FIGS. 2 and 3, when a droplet of oil or the like flows along the inner wall of the airflow tube 6, it is guided to the lowermost position A of the slope by the annular step portion 11 and below it. It flows to the position C on the outer peripheral side of the throttle valve 5. As described above, the position C is the position farthest from the opening / closing shaft 5a, and there is no fear that droplets adhere to the opening / closing shaft 5a. Further, since the position C is a position where the throttle valve 5 moves downward when the throttle valve 5 is opened, the liquid drops further flow when the throttle valve 5 is opened. Will not be disturbed. Furthermore, to enlarged the intake passage gradually as the annular recess 10 which is recessed an intake passage wall, by forming the annular step portion 11 at the lower end of its intake passage be reduced in diameter by the annular step Since the cross-sectional area of the air does not decrease, the intake flow is less likely to be disturbed.
[0011]
【The invention's effect】
As evidenced by the foregoing description, according to the intake system of an internal combustion engine according to the present invention, fear of closing shaft and bearings of the throttle valve is stained eliminates the droplets of oil droplet like in easy single structure. In particular, the inner surface of the intake passage and gradually increased in diameter toward the lower side to form an annular recess, by forming the annular step portion having an upper surface inclined to its lower end, is prevented from disturbing the intake air flow. Furthermore, since the annular step is integrally formed in the air flow tube that connects the air cleaner and the throttle body with the throttle valve, a guide structure can be realized by simply devising the shape of the intake passage wall. Becomes easier.
[Brief description of the drawings]
FIG. 1 is a front perspective view of an in-line four-cylinder engine as an internal combustion engine to which the present invention is applied.
2 is a side sectional view of the periphery of a throttle valve in an intake passage of the engine of FIG. 1;
3 is a cross-sectional view taken along line III-III in FIG.
FIG. 4 is a cross-sectional view showing a connection portion of a breather tube to an air cleaner.
[Explanation of symbols]
2 Intake manifold 4 Throttle body 5 Throttle valve 5a Open / close shaft 6 Air flow tube 6a Hanging part 7 Air cleaner 8 Blow-by gas recirculation pipe 10 Annular recess 11 Annular step

Claims (2)

An intake device for an internal combustion engine having a blow-by gas discharge port upstream of a throttle valve in a downflow type intake passage,
Between the throttle valve and the blow-by gas discharge port in the intake passage wall of the intake passage, an annular recess that gradually increases in diameter from above to below is formed,
An upper surface inclined downward to correspond to a side moving downward when the throttle valve is opened, in order to guide a liquid droplet to a lower side of the annular recess toward a side moving downward when the throttle valve is opened. An air intake device for an internal combustion engine, characterized in that an annular step portion having the following is formed . 2. The intake device for an internal combustion engine according to claim 1, wherein the annular step portion is formed integrally with the air flow tube in an air flow tube that connects a throttle body including the throttle valve and an air cleaner .

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