JPH07259529A - Inlet pipe structure in internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent any sticking of oil in the gas of positive crankcase ventilation to a throttle valve from occurring. CONSTITUTION:A rib 9 is installed in an inner surface on the upper wall of a surge tank 2 lying between an opening part 6 of a PCV passage 5 and a throttle valve. A step difference 10 overhung with the upper side is installed in a split part between this surge tank 2 and an intake manifold 3. A gasket lying between the surge tank 2 and this manifold 3 is projected inward from a surge tank side wall surface. Backflow oil is caught either of the surge tank or the intake manifold, dropping it down, whereby the oil is prevented from flowing into the throttle valve. In addition. When the gasket is projected out, a smoothly curved throat part is formed in an inner end of the gasket and thereby a reduction in intake resistance, long-port formation or the like are thus promotable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake pipe structure for an internal combustion engine, and more particularly to a structure for improving prevention of deposits on a throttle valve.

[0002]

2. Description of the Related Art As disclosed in Japanese Utility Model Laid-Open No. 2-119970, a PCV (positive crankcase ventilation) passage is opened downstream of a throttle valve of an intake system to guide blow-by gas to the intake passage. However, if a negative pressure when the throttle valve is closed or intake pulsation causes a reverse flow of intake air downstream of the throttle valve, some of the oil in the blow-by gas adhering to the inner wall of the surge tank or intake manifold will flow toward the throttle valve. May be attracted to the throttle valve, deposit on the throttle valve and deposit, and eventually the throttle valve may become stuck. In order to prevent this, various measures have been conventionally taken. For example, Japanese Utility Model Laid-Open No. 2-119970 proposes to provide a projection on the inner wall of the intake pipe near the throttle valve to stop the reverse flow of oil by the projection. is doing.

[0003]

However, in the above structure, the deposit continues to be deposited on the protrusion so that the protrusion becomes smooth and the oil drawn toward the throttle valve easily gets over the protrusion. turn into. Therefore, there is a problem in that it is impossible to prevent deposits from accumulating in the throttle valve portion over a long period of time. An object of the present invention is to provide an intake pipe structure for an internal combustion engine, which allows oil to flow to the internal combustion engine side by its own weight and improves prevention of deposit adhesion to a throttle valve.

[0004]

The intake structure of an internal combustion engine of the present invention for achieving the above object is as follows. (1) In the intake pipe structure of an internal combustion engine, wherein a surge tank having an intake port opened is provided downstream of the throttle valve, and an opening of a PCV passage is provided in the surge tank.
An intake pipe structure for an internal combustion engine, wherein ribs are provided on an inner surface of an upper wall of a surge tank between an opening of a CV passage and the throttle valve, the ribs facing each other in an intake flow direction and having an end extending near an intake port. (2) An internal combustion engine in which a surge tank is provided downstream of the throttle valve, an intake manifold is connected to a lower side of the surge tank, a PCV passage opening is provided in the surge tank, and a branch pipe opening is provided in the intake manifold. An intake pipe structure for an internal combustion engine, wherein, in the intake pipe structure of the engine, a step is provided at a split portion between the surge tank and the intake manifold, and the surge tank has a step protruding inward from the intake manifold. (3) Internal combustion engine in which a surge tank is provided downstream of the throttle valve, an intake manifold is connected to the lower side of the surge tank, a PCV passage opening is provided in the surge tank, and a branch pipe opening is provided in the intake manifold. In an intake pipe structure for an engine, an intake pipe structure for an internal combustion engine, wherein a gasket provided between the surge tank and the intake manifold is protruded inward from an inner surface of a side wall of the surge tank and the intake manifold. (4) Internal combustion engine in which a surge tank is provided downstream of the throttle valve, an intake manifold is connected to a lower side of the surge tank, a PCV passage opening is provided in the surge tank, and a branch pipe opening is provided in the intake manifold. In an intake pipe structure of an engine, a gasket provided between the surge tank and the intake manifold is projected inward from an inner surface of a side wall of the surge tank and the intake manifold, and further, an inner end portion of the gasket has a wall on the side of the branch pipe. An intake pipe structure for an internal combustion engine, which is smoothly curved, has a passage cross-sectional shape that is substantially the same as the passage cross-sectional shape of the branch pipe, and whose tip is stopped immediately upstream of the branch pipe to form a throat portion. (5) An internal combustion engine in which a surge tank is provided downstream of the throttle valve, an intake manifold is connected to a lower side of the surge tank, a PCV passage opening is provided in the surge tank, and a branch pipe opening is provided in the intake manifold. In an intake pipe structure of an engine, a gasket provided between the surge tank and the intake manifold is projected inward from an inner surface of a side wall of the surge tank and the intake manifold, and further, an inner end portion of the gasket has a wall on the side of the branch pipe. Intake of an internal combustion engine having a throat portion, which is smoothly curved, has a passage cross-sectional shape that is substantially similar to the passage cross-sectional shape of the branch pipe and is reduced, and has a tip extending to the inner peripheral portion of the branch pipe. Tube structure.

[0005]

In the intake pipe structure of the above (1), the ribs reliably catch the oil that adheres to the inner surface of the surge tank and is drawn toward the throttle valve toward the throttle valve by the negative pressure. It flows through the manifold to the engine and is burned in the engine combustion chamber. Therefore, the situation where the oil flows to the throttle valve to generate a deposit to fix the throttle valve does not occur. In the intake pipe structure of the above (2), when the oil attached to the inner surface of the intake manifold is pulled toward the throttle valve side by the negative pressure, it is stopped by the step and falls from there by its own weight. For this reason, oil can be prevented from flowing to the throttle valve, and sticking due to deposit of the throttle valve can be prevented. In the intake pipe structure of the above (3), the same action and effect as the step of the structure of the above (2) can be obtained only by overhanging the gasket. In the intake pipe structure of (4), in addition to the action of (3), even if the inlet corner portion of the branch pipe of the intake manifold is not shaved by machining, the smoothly curved throat portion reduces the flow resistance of intake air. The effect of being reduced is obtained. In the intake pipe structure of the above (5), in addition to the action of the above (4), the branch pipe length can be substantially increased by the throat portion extended into the branch pipe without redesigning the intake manifold, It is possible to obtain the effect of being used for reducing intake noise.

[0006]

1 to 7 show an embodiment of the present invention.
Of these, FIG. 1 shows a general structure applicable to all the embodiments, parts of FIGS. 2 and 3 show the first embodiment of the present invention (corresponding to claim 1), and other parts of FIG. 3 show the present invention. 4 is a second embodiment (corresponding to claim 2) of the present invention, FIG. 4 is a third embodiment of the present invention (corresponding to claim 3), and FIGS. 5 and 6 are a fourth embodiment of the present invention (claim 4). 7) and FIG. 7 shows a fifth embodiment of the present invention (corresponding to claim 5). First, the general configuration will be described with reference to FIG. The intake pipe of the internal combustion engine includes a throttle valve 1, a surge tank 2 downstream of the throttle valve 1,
It has an intake manifold 3 connected to the surge tank 2 from below, and a gasket 4 interposed between the surge tank 2 and the intake manifold 3. The upper side of the space inside the surge tank is covered by the surge tank 2, and the lower side is covered by the intake manifold 3. Therefore, the surge tank 2 and the intake manifold 3 have a relationship between the upper portion and the lower portion when the integral type surge tank is divided into two.

The surge tank 2 is provided with an opening 6 to the intake pipe of the PCV passage 5 for returning blow-by gas from the inside of the crankcase and the cylinder head cover to the intake pipe of the internal combustion engine. On the other hand, the upstream opening 8 of the branch pipe 7 that guides the intake air in the surge tank to each cylinder of the internal combustion engine is open to the intake manifold 3.

Next, each embodiment of the present invention will be described. In the first embodiment of the present invention, as shown in FIGS. 2 and 3, one or more ribs 9 are provided on the inner surface of the upper wall of the surge tank 2 between the opening 6 of the PCV passage 5 and the throttle valve 1. (Two in the illustrated example) are provided. The rib 9 is orthogonal or substantially orthogonal to the intake air flow direction (longitudinal direction of the surge tank). The axis of the opening 6 of the PCV passage 5 extends in a direction orthogonal or substantially orthogonal to the intake air flow direction (longitudinal direction of the surge tank), and is a tangential direction or a tangential line of a curve of the surge tank upper wall. Extending in the direction. Therefore, the blow-by gas flows from the opening 6 of the PCV passage 5 into the space inside the surge tank in the direction parallel to the rib 9 along the inner surface of the upper wall of the surge tank (is sucked by the negative pressure downstream of the throttle).

In the second embodiment of the present invention, as shown in FIG. 3 which is a cross section A, a step 10 is provided at a division portion between the surge tank 2 and the intake manifold 3. Step 10
Is provided at the front of the opening 6 in the blow-by gas blowing direction, at the split portion between the surge tank 2 and the intake manifold 3. This step 10 causes the inner surface of the surge tank 2 to project more toward the inside of the surge tank than the inner surface of the intake manifold 3, and at that time, the lower surface of the flange portion of the surge tank is substantially orthogonal to the inner surface of the intake manifold side wall to the inside of the surge tank. It consists of a step formed by protruding.

In the third embodiment of the present invention, as shown in FIG. 4, the gasket 4 interposed between the surge tank 2 and the intake manifold 3 has an inner surface of the side wall of the surge tank 2 and the side wall of the intake manifold 3. It projects more toward the inside of the surge tank than the inner surface of. The protruding tip of the gasket 4 is smoothly curved downward.

In the fourth embodiment of the present invention, as shown in FIG. 5 and FIG. 6, the gasket 4 interposed between the surge tank 2 and the intake manifold 3 is provided with the inner surface of the side wall of the surge tank 2 and the intake. It projects toward the inside of the surge tank from the inner surface of the side wall of the manifold 3. A throat portion (throat portion having a narrowed passage cross section) 11 is formed at an inner end portion of the gasket 4. The gasket wall forming the throat portion 11 is smoothly curved on the side of the branch pipe 7,
It is curved with R larger than R at the corner portion of the branch pipe inlet. The passage cross-sectional shape of the throat portion 11 is substantially the same as the passage cross-sectional shape of the branch pipe 7 located on the downstream side. After the gasket 4 is curved toward the branch pipe, the throat portion 1
The inner tip of 1 ends immediately upstream of the inlet of the branch pipe 7, and there is a slight gap in the longitudinal direction of the branch pipe between the tip of the throat portion 11 and the inlet of the branch pipe 7. .

In the fifth embodiment of the present invention, as shown in FIG. 7, the gasket 4 interposed between the surge tank 2 and the intake manifold 3 has the inner surface of the side wall of the surge tank 2 and the intake manifold 3. It projects toward the inside of the surge tank rather than the inner surface of the side wall. A throat portion (throat portion having a narrowed passage cross section) 11 is formed at an inner end portion of the gasket 4. The gasket wall forming the throat portion 11 is smoothly curved on the side of the branch pipe 7, and is curved with R larger than R at the corner portion of the branch pipe inlet. The cross-sectional shape of the passage of the throat portion 11 is substantially similar to the cross-sectional shape of the branch pipe 7 located on the downstream side and is reduced.
After the gasket 4 is curved to the side of the branch pipe, the inner tip of the throat portion 11 ends by being thrust into the branch pipe 7, and between the throat portion 11 and the branch pipe 7 in the radial direction of the branch pipe. There is a slight gap.

Next, the operation will be described. In common with all the embodiments, the intake air is sucked by the internal combustion engine, flows from the throttle valve 1 into the space surrounded by the surge tank 2 and the intake manifold 3, and further branches.
Through to each cylinder. On the other hand, the blow-by gas from the PCV passage 5 flows into the surge tank, and part of the oil mist contained in the blow-by gas adheres to the inner surface of the intake pipe. When the throttle valve 1 is closed, such as at idle,
Negative pressure occurs downstream of the throttle valve 1. At this time, the intake air that has passed through the slight gap between the throttle valve and the intake pipe wall is caught downstream of the throttle valve 1 and a partial backflow occurs. In addition, backflow due to intake pulsation also occurs in the branch pipe 7 connected to each cylinder. When these backflows occur, the oil adhering to the inner surface of the intake pipe will pass through the inner surface of the intake pipe, and the throttle valve 1
It flows toward the side. If the oil reaches the throttle valve 1 and deposits are accumulated on the throttle valve 1, there is a risk that the throttle valve 1 may become stuck to the wall of the intake pipe, so it must be prevented from reaching the throttle valve 1.

The function of preventing the backflow oil from reaching the throttle valve 1 is different in each embodiment. In the first embodiment of the present invention, the rib 9 catches the oil flowing toward the throttle valve 1 along the inner surface of the upper wall of the surge tank and drops it into the branch pipe 7 of the intake manifold 3 below by gravity. Since the intake air flows at the lower ends of the ribs 9, the oil is well cut off from the ribs 9 and the oil is prevented from flowing over the ribs 9 to the throttle valve 1 side through the wall surface. Further, since the blow-by gas is introduced from the PCV passage opening 6 along the inner surface of the surge tank upper wall, the oil mist does not scatter in all directions as in the case where the blow-by gas is opened orthogonally to the surge tank. Therefore, the scattered oil adheres to the wall surface on the upstream side of the rib 9 or the rib 9
It is also suppressed that the reverse intake air flows on the upstream side.

In the second embodiment of the present invention, when the oil that has dropped to the intake manifold 3 and adhered to the wall surface of the intake manifold flows to the throttle valve 1 side due to the reverse flow of intake air and reaches the step 10, the flow is stopped by the step 10. From there, it falls by gravity onto the bottom wall of the intake manifold or the branch pipe 7. Since the inner tip of the step 10 is exposed to the flow of intake air, the oil can be cut off from the inner tip of the step. As a result, the oil is prevented from passing over the step 10 and further flowing to the throttle valve side.

In the third embodiment of the present invention, the surge tank 2
The gasket 4 at the division between the intake manifold and the intake manifold 3.
Is projected inward from the wall surface, the discharge portion of the gasket 4 catches the backflow oil flowing from the intake manifold 3 to the surge tank 2 along the wall surface, and drops it by its own weight downward from the tip of the projection portion. In this case, if the tip portion of the gasket protruding portion is curved downward, the oil can be easily cut off from the gasket tip. In addition, deposit accumulation on the gasket 4 is suppressed to that extent, and it is not necessary to replace the gasket 4.

In the fourth embodiment of the present invention, since the gasket 4 projects toward the inside of the surge tank, all the effects of the third embodiment of the present invention can be obtained. In addition, in the fourth embodiment of the present invention, since the throat portion 11 is formed at the inner end of the gasket 4 and the wall of the throat portion 11 is smoothly curved toward the branch pipe 7, the throat portion 11 is formed. The intake resistance is small when intake air flows into the throat portion 11 from the inside of the surge tank on the upstream side. Conventionally, gasket 4
In order to reduce the flow resistance of the intake air flowing into the branch pipe from the space inside the surge tank, the corner portion of the branch pipe inlet portion had to be machined to be cut off. However, the fourth embodiment of the present invention In the example, since the intake air that has passed through the throat portion 11 smoothly enters the branch pipe 7 as it is, it is not necessary to cut the inlet corner portion of the branch pipe 7 by machining. Therefore, the intake resistance is reduced without increasing the number of processes.

In the fifth embodiment of the present invention, since the gasket 4 has the throat portion 11 having the wall smoothly curved on the side of the branch pipe at the inner end, all the effects of the fourth embodiment of the present invention can be obtained. To be In addition, in the fifth embodiment of the present invention, since the tip of the throat portion 11 projects into the branch pipe 7, the length of the branch pipe 7 is substantially increased by the throat portion 11,
The branch pipe 7 has a long port. With this long port, the substantial length of the engine and the space inside the surge tank changes, and the reflection position of the intake sound changes, which can be used to reduce the intake sound. Further, in the case of making the port long and improving the low and medium speed performance of the engine, it is general to reduce the surge tank volume for that purpose, but in the fifth embodiment of the present invention, the throat portion 11 and the intake Since the volume surrounded by the manifold 3 becomes a dead volume, the surge tank volume can be naturally reduced. Conventionally, in order to make the branch pipe 7 a long port, it was necessary to redone the entire design of the intake manifold and the branch pipe, but in the fifth embodiment of the present invention, only the gasket is changed. Can handle.

[0019]

According to the intake pipe structure of the internal combustion engine of the first aspect, since the rib catches the oil flowing toward the throttle valve and drops it, deposits are not deposited on the throttle valve, and sticking due to the deposit of the throttle valve is prevented. It can be prevented. According to the intake pipe structure of the internal combustion engine of claim 2, since the step catches the backflow oil from the intake manifold to the surge tank and drops it, the sticking of the throttle valve due to the deposit of the backflow oil from the intake manifold to the throttle valve is prevented. It can be prevented. According to the intake pipe structure of the internal combustion engine of claim 3, since the gasket catches the backflow oil from the intake manifold to the surge tank and drops it, the sticking of the throttle valve due to the backflow of oil from the intake manifold to the throttle valve is prevented. It can be prevented. According to the intake pipe structure of the internal combustion engine of claim 4, in addition to the effect of the structure of claim 3, a throat portion whose wall is smoothly curved toward the branch pipe is formed at the inner end portion of the gasket. The intake resistance can be reduced, and the output performance of the internal combustion engine can be correspondingly increased. According to the intake pipe structure of the internal combustion engine of claim 5, in addition to the effect obtained by the structure of claim 4, since the throat portion is projected into the branch pipe, the branch pipe has a long port, thereby reducing intake noise. Therefore, the output of the internal combustion engine can be improved.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an intake pipe structure of an internal combustion engine applicable to all embodiments of the present invention.

FIG. 2 is an exploded perspective view of the intake pipe structure of the internal combustion engine of the first embodiment of the present invention.

FIG. 3 is a cross-sectional view of the intake pipe structure of the internal combustion engine according to the first and second embodiments of the present invention, which is taken along the line A in FIGS. 1 and 2.

FIG. 4 is a sectional view of an intake pipe structure for an internal combustion engine according to a third embodiment of the present invention.

FIG. 5 is an exploded perspective view of an intake pipe structure for an internal combustion engine according to a fourth embodiment of the present invention.

FIG. 6 is a sectional view of an intake pipe structure for an internal combustion engine according to a fourth embodiment of the present invention.

FIG. 7 is a sectional view of an intake pipe structure for an internal combustion engine according to a fifth embodiment of the present invention.

[Explanation of symbols]

 1 Throttle Valve 2 Surge Tank 3 Intake Manifold 4 Gasket 5 PCV Passage 6 PCV Passage Opening 7 Branch Pipe 8 Branch Pipe Opening 9 Rib 10 Step 11 Throat

Claims (5)

[Claims] 1. A surge tank having an intake port opened is provided downstream of the throttle valve, and a PCV is provided in the surge tank.
In the intake pipe structure of the internal combustion engine provided with the passage opening,
An intake pipe for an internal combustion engine, characterized in that an inner wall of a surge tank upper wall between the opening of the PCV passage and the throttle valve is provided with a rib facing the intake flow direction and having an end extending near the intake port. Construction. 2. A surge tank is provided downstream of the throttle valve, an intake manifold is connected to a lower side of the surge tank, a PCV passage opening is provided in the surge tank, and a branch pipe opening is provided in the intake manifold. In the intake pipe structure of the internal combustion engine, the surge tank is provided with a step projecting inward from the intake manifold at a divided portion between the surge tank and the intake manifold. 3. A surge tank is provided downstream of the throttle valve, an intake manifold is connected to a lower side of the surge tank, a PCV passage opening is provided in the surge tank, and a branch pipe opening is provided in the intake manifold. In an intake pipe structure for an internal combustion engine, a gasket provided between the surge tank and the intake manifold is projected inward from a side wall inner surface of the surge tank and the intake manifold. 4. A surge tank is provided downstream of the throttle valve, an intake manifold is connected to a lower side of the surge tank, a PCV passage opening is provided in the surge tank, and a branch pipe opening is provided in the intake manifold. In the intake pipe structure of an internal combustion engine, a gasket provided between the surge tank and the intake manifold is projected inward from a side wall inner surface of the surge tank and the intake manifold, and further at an inner end portion of the gasket,
The wall is smoothly curved to the side of the branch pipe, the cross-sectional shape of the passage is substantially the same as the cross-sectional shape of the passage of the branch pipe, and a tip is formed immediately upstream of the branch pipe to form a throat portion. Intake pipe structure of internal combustion engine. 5. A surge tank is provided downstream of the throttle valve, an intake manifold is connected to a lower side of the surge tank, a PCV passage opening is provided in the surge tank, and a branch pipe opening is provided in the intake manifold. In the intake pipe structure of an internal combustion engine, a gasket provided between the surge tank and the intake manifold is projected inward from a side wall inner surface of the surge tank and the intake manifold, and further at an inner end portion of the gasket,
The wall is smoothly curved on the side of the branch pipe, and the passage cross-sectional shape is substantially similar to the passage cross-sectional shape of the branch pipe and is reduced;
An intake pipe structure for an internal combustion engine, wherein a throat portion is formed whose tip extends to an inner peripheral portion of the branch pipe.