JP2009293499A - Oil return structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oil return structure of an internal combustion engine capable of preventing the deterioration of oil while preventing the reverse flowing of blowby gas to a gas-liquid separation chamber. <P>SOLUTION: The oil return structure is constituted so that oil in the blowby gas separated by the gas-liquid chamber 6 in a cylinder head cover 2 is discharged to an upper deck 4 side of a cylinder head 1 from an oil discharge pipe 7 suspended from a bottom face of the gas-liquid separation chamber 6. The oil discharge pipe 7 is arranged so that a discharge opening of a lower end discharging oil projects into a recessed part 8 formed at an inclined face 4a of an upper deck 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an oil return structure for returning oil in blow-by gas to an oil pan.

Conventionally, as this kind of oil return structure, oil in blow-by gas is separated in a gas-liquid separation chamber provided in the cylinder head cover, and the separated oil is suspended in the bottom of the gas-liquid separation chamber. Has been proposed to be discharged to the valve chamber side.
In this oil return structure, the lower end side of the oil drain pipe is bent into an S-shape, and the oil flowing down to the oil drain pipe is retained in the bent portion so that the gas-liquid separation chamber and the valve operating chamber The ventilation with the side is cut off. That is, according to the structure described above, the oil separated in the gas-liquid separation chamber is discharged to the valve operating chamber side while preventing the blow-by gas from flowing back from the oil drain pipe to the gas-liquid separation chamber.
Japanese Patent Laid-Open No. 10-30423

  However, in such an oil return structure, the oil staying in the bent portion of the oil drain pipe is difficult to be exchanged, so that the oil drain pipe is easily deteriorated. It couldn't be said.

The oil return structure of the present invention has one of the purposes of simply ensuring a structure that prevents the deterioration of oil while preventing the backflow of blow-by gas to the gas-liquid separator, and at least part of the purpose is The following measures were taken to achieve this.
The present invention is an oil return structure for discharging oil in a blow-by gas separated by a gas-liquid separation unit to an upper deck side of a cylinder head from an oil discharge pipe suspended from the bottom surface of the gas-liquid separation unit, The gist of the oil discharge pipe is that a tip end portion in which a discharge opening for discharging the oil is formed so as to protrude into a recess provided on the upper deck.

  According to the oil return structure of the present invention, it is only necessary to project the distal end portion of the oil discharge pipe into the recess provided on the upper deck, so that the gas-liquid separation portion and the valve chamber on the upper deck side are connected. Can block ventilation. That is, during operation of the internal combustion engine, oil after lubricating the valve mechanism disposed in the valve chamber flows through the upper deck, and oil always accumulates in the recesses. Ventilation with the valve chamber can be blocked, and the oil constantly flows on the upper deck during the operation of the internal combustion engine, so that the oil in the recess is always replaced. As a result, it is possible to easily ensure a structure that prevents the deterioration of the oil while preventing the backflow of the blow-by gas to the gas-liquid separator. Of course, the oil separated in the gas-liquid separator can be discharged from the oil discharge pipe.

In the oil return structure of the present invention, the upper deck may be formed with an inclined surface, and the recess may be provided in the inclined surface.
By so doing, the concave portion is provided in the portion of the upper deck where the oil always flows, so that the oil in the concave portion can be reliably replaced.

In the oil return structure of the present invention, the upper deck is formed with a return hole for returning the oil to the oil pan, and the inclined surface is formed to guide the oil to the return hole. It can also be set as the structure formed.
In this case, since the inclined surface formed for guiding the oil on the upper deck to the return hole can be used as the inclined surface for providing the recess, it is not necessary to separately form the inclined surface for providing the recess.

Moreover, the oil return structure of this invention WHEREIN: The said recessed part can also be made into the structure formed by being recessedly provided in the said upper deck.
In this way, it is possible to easily secure the recess on the upper deck.

In the oil return structure of the present invention, the cylinder head is formed with a water jacket, and the upper deck has a core hole made of a baseboard for a water jacket core for forming the water jacket. The recess may be formed by using a plug that closes the core hole.
In this way, it is possible to easily secure the recess on the upper deck.

In the oil return structure of the present invention, the recess may be formed by a core hole and a plug that closes the core hole.
In this way, it is possible to easily secure the recess on the upper deck.

  Next, the best mode for carrying out the present invention will be described using examples.

  FIG. 1 is a schematic vertical cross-sectional configuration diagram of a cylinder head and a cylinder head cover portion of the internal combustion engine (showing a cross section taken along the line AA in FIG. 3), and FIG. 2 is an enlarged configuration diagram of a main part of FIG. FIG. 3 is a plan view of the cylinder head.

  As shown in FIG. 1, the cylinder head 1 of the internal combustion engine includes an intake valve (not shown), an exhaust valve (not shown), and a valve lifter (not shown) between the intake valve and the exhaust valve (not shown). The upper deck 4 includes an upper deck 4 that defines a valve operating chamber 3 that accommodates a valve operating mechanism including camshafts 13a and 13b that are directly driven through the lower deck 40, and a lower deck 40 that forms a combustion chamber (not shown). A water jacket 9 that circulates cooling water in the cylinder row direction is formed in a region surrounded by the lower deck 40.

The upper deck 4 has inclined inclined surfaces 4a and 4a formed such that the height thereof decreases from the center of the cylinder row passing through the center of each cylinder toward both side walls.
As shown in FIGS. 1 and 3, the upper deck 4 has an oil return hole 5 penetrating from the upper deck 4 to the lower deck 40 at a position substantially in the center in the cylinder row direction and protruding slightly outward from both side walls. , 5 are formed as openings, and oil flowing down on the upper deck 4 is returned to an oil pan (not shown) through the oil return holes 5, 5.
Further, a concave portion 8 is formed in a concave shape in the middle of one of the inclined surfaces 4a and 4a of the upper deck 4 (the inclined surface 4a located on the left side in FIG. 2).
In the figure, reference numeral 10 denotes a bolt hole through which a bolt for attaching the cylinder head 1 to a cylinder block (not shown), and 11 and 12 in the figure are valve seats of the exhaust port and the intake port, respectively. 14a and 14b in the figure are cam brackets that rotatably support the exhaust-side camshaft 13a and the intake-side camshaft 13b, respectively.

On the other hand, in the cylinder head cover 2, a blow-by gas passage and a gas-liquid separation chamber 6 forming a bypass-like passage for separating oil in the blow-by gas are formed as a gas-liquid separation portion.
In this example, a pipe-like oil discharge pipe 7 is suspended from the bottom surface 6 a of the gas-liquid separation chamber 6. A discharge opening 7 a at the lower end of the oil discharge pipe 7 protrudes into a recess 8 formed in a recessed shape on the inclined surface 4 a on the left side of the upper deck 4 in the figure.
The upper end of the oil discharge pipe 7 is fixed by welding in a state where the upper end is opened in an oil sump 6b formed by being recessed in the bottom surface 6a of the gas-liquid separation chamber 6.

Next, the movement of oil in the oil return structure of the internal combustion engine configured as described above, in particular, the movement of oil separated from blow-by gas in the gas-liquid separation chamber 6 will be described.
When the operation of the internal combustion engine is started, blow-by gas flows from a crankcase (not shown) into the gas-liquid separator through the valve operating chamber 3. The blow-by gas that has flowed into the gas-liquid separator is subjected to gas-liquid separation in the gas-liquid separation chamber 6. That is, the oil in the blow-by gas is separated in the gas-liquid separation chamber 6. The separated oil passes through the oil discharge pipe 7 via the oil reservoir 6 b on the bottom surface 6 a of the gas-liquid separation chamber 6 and is discharged into the recess 8 formed in the inclined surface 4 a of the upper deck 4.
Here, during the operation of the internal combustion engine, oil is supplied into the valve operating chamber 3 in order to lubricate the valve operating mechanisms such as the cam, the intake valve, and the exhaust valve. On the upper deck 4, the oil always flows along the inclined surfaces 4 a and 4 a, and therefore oil is always accumulated in the recess 8. Moreover, the oil in the recess 8 is always replaced.
Since the recess 8 is formed only on the inclined surfaces 4a and 4a formed to guide the oil on the upper deck 4 to the oil return holes 5 and 5, the structure for replacing the oil in the recess 8 can be simplified. It can be secured.

  Since the discharge opening 7a at the lower end of the oil discharge pipe 7 protrudes into the recess 8, the oil flowing in the oil discharge pipe 7 and the oil accumulated in the recess 8 are used for the inside of the valve chamber 3 and the gas-liquid separation chamber. The ventilation with 6 is blocked. As a result, the oil separated in the gas-liquid separation chamber 6 can be discharged while satisfactorily preventing the reverse flow of blow-by gas from the valve operating chamber 3 to the gas-liquid separation chamber 6. Moreover, since the oil flowing down the oil discharge pipe 7 and the oil accumulated in the recess 8 are always replaced during the operation of the internal combustion engine, the oil flowing down the oil discharge pipe 7 and the oil accumulated in the recess 8 deteriorate. There is nothing.

Thus, the oil in the blow-by gas separated in the gas-liquid separation chamber 6 can be discharged while favorably preventing the reverse flow of the blow-by gas from the valve operating chamber 3 to the gas-liquid separation chamber 6 with a simple structure. Moreover, the oil flowing down the oil discharge pipe 7 and the oil accumulated in the recess 8 are not deteriorated.
The arrows in FIG. 3 indicate the flow of oil during operation of the internal combustion engine. The oil flows on the inclined surfaces 4a, 4a of the upper deck 4 to the left and right sides, and part of the oil return hole 5 , 5, the remainder is returned to the oil pan through an opening (not shown) communicating the valve mechanism chamber 3 and a chain chamber (not shown).

  In the first embodiment, the concave portion 8 is formed on the inclined surface 4a formed on the upper deck 4 in order to guide the oil on the upper deck 4 to the oil return holes 5 and 5, but the oil in the concave portion 8 is As long as it can be replaced, an inclined surface may be formed separately from the inclined surface 4a, and the recessed portion 8 may be formed on the inclined surface. Other than the upper deck 4, for example, a side wall forming the valve operating chamber 3, etc. It is also possible to form a recess 8 on the inclined surface by projecting the inclined surface.

4, 5 and 6 show a second embodiment.
4 is a schematic vertical cross-sectional view of the cylinder head and cylinder head cover of the second embodiment (showing a cross-sectional view taken along the line BB in FIG. 6), and FIG. 5 is an enlarged view of the main part of FIG. . FIG. 6 is a plan view of the cylinder head.

Also in the second embodiment, an oil discharge pipe 7 is suspended from the bottom surface 6a of the gas-liquid separation chamber 6 in the cylinder head cover 2, but this oil discharge pipe 7 is not a straight pipe but is bent gently downward. The upper deck 4 has a discharge opening 7a at the lower end facing the center in the left-right direction.
A core hole 9 a communicating with the lower water jacket 9 is formed at the center in the left-right direction of the upper deck 4 of the cylinder head 1. The core hole 9a is formed by a baseboard for a water jacket core at the time of casting, and the core hole 9a serves to position and sand the water jacket core at the time of casting. is there.

In this example, the core hole 9a is used to attach the plug 15 to the core hole 9a by screwing or press fitting. The plug 15 that closes the core hole 9a has a bottomed cylindrical shape with a recess 15a having an open upper surface, and the upper surface of the plug 15 is substantially flush with the upper surface of the upper deck 4. The oil flowing down on the upper deck 4 is configured to accumulate in a recess 15a formed in the plug 15, and a discharge opening 7a at the lower end of the oil discharge pipe 7 projects into the recess 15a.
Accordingly, the discharge opening 7a of the oil discharge pipe 7 is immersed in the oil stored in the recess 15a, and the oil after lubricating the valve mechanism in the valve chamber 3 is always kept in this position during the operation of the internal combustion engine. Since the oil flows into the concave portion 15a, the oil in the concave portion 15a is always replaced and does not stay and deteriorate.
In this way, the trap structure is formed by the recess 15a of the plug 15 and the discharge opening 7a of the oil discharge pipe 7 immersed in the oil in the recess 15a, and the ventilation between the valve chamber 3 and the gas-liquid separation chamber 6 is made. Is prevented from flowing back through the oil discharge pipe 7 to the gas-liquid separation chamber 6 side.

In this way, in this example, by using the core hole 9a formed by the core of the water jacket core, the plug 15 that closes the core hole 9a is formed with the recess 15a having an open upper surface, and the recess 15a. The structure in which the discharge opening 7a at the lower end of the oil discharge pipe 7 vertically suspended from the gas-liquid separation chamber 6 is faced to prevent the deterioration of oil while preventing the backflow of blow-by gas to the gas-liquid separation chamber 6. It is something that can be done.
In such a structure, it is not necessary to separately form the recess 8 in the inclined surface 4a of the upper deck 4 as in the first embodiment, and the core hole 9a can be used satisfactorily.
The other structure is the same as that of the first embodiment, and the same members are denoted by the same reference numerals and the description thereof is omitted.

Next, FIG. 7 shows a third embodiment, and FIG. 7 is an enlarged configuration diagram of a main part of the third embodiment.
In the third embodiment, the plug 15 is screwed or press-fitted into the core hole 9a formed at the center in the left-right direction of the upper deck 4, and the recess 8 is formed by the core hole 9a above the plug 15. is there.
That is, the upper surface of the plug 15 is disposed below the upper end of the core hole 9a, and the recess 15 is formed at the center in the left-right direction of the upper deck 4 by the plug 15 that closes the core hole 9a.

  A discharge opening 7a at the lower end of an oil discharge pipe 7 suspended from the gas-liquid separation chamber 6 is faced in the recess 8, and the valve chamber 3 is always in the recess 8 during operation of the internal combustion engine. Since the oil lubricated in the valve mechanism flows down and is stored, and the oil is always replaced, the oil in the recess 8 is not deteriorated, and the oil discharge pipe 7 is placed in the oil stored in the recess 8. Since the discharge opening 7a at the lower end can be kept immersed, the blow-by gas is not blocked by the oil stored in the recess 8 and flows back from the oil discharge pipe 7 to the gas-liquid separation chamber 6 side. The backflow of blow-by gas can be prevented well.

  Also in this example, the core hole 9a formed by the core jacket for the water jacket is effectively used, and the plug 15 is fixed in the core hole 9a, and the core hole 9a above the plug 15 is fixed. The concave portion 8 can be formed satisfactorily, and deterioration of oil can be prevented with a simple structure while preventing the backflow of blow-by gas.

It is a schematic longitudinal cross-section block diagram (the AA line cross-section block diagram of FIG. 3) of the cylinder head and cylinder head cover of 1st Example. It is a principal part expanded block diagram of FIG. It is a plane block diagram of a cylinder head. It is a longitudinal cross-sectional schematic block diagram of the cylinder head and cylinder head cover of 2nd Example (BB sectional view taken on the line of FIG. 6). It is a principal part expanded block diagram of FIG. It is a plane block diagram of a cylinder head. It is a principal part expanded block diagram which shows 3rd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder head 2 Cylinder head cover 3 Valve operating chamber 4 Upper deck 4a Inclined surface 5 Return hole 6 Gas-liquid separation chamber 6a Bottom surface 7 Oil discharge pipe 7a Discharge opening 8 Recess 9 Water jacket 9a Core hole 10 Bolt hole 15 Plug 15a Recess

Claims (6)

An oil return structure for discharging the oil in the blow-by gas separated by the gas-liquid separation unit to the upper deck side of the cylinder head from an oil discharge pipe suspended from the bottom of the gas-liquid separation unit,
The oil discharge pipe is arranged so that a front end portion in which a discharge opening for discharging the oil is formed protrudes into a recess provided on the upper deck. The upper deck is formed with an inclined surface,
The oil return structure according to claim 1, wherein the recess is provided in the inclined surface. The upper deck is formed with a return hole for returning the oil to the oil pan.
The oil return structure according to claim 2, wherein the inclined surface is formed to guide the oil to the return hole.   The oil return structure according to any one of claims 1 to 3, wherein the recess is provided in the upper deck. The cylinder head is formed with a water jacket,
In the upper deck, a core hole made of a baseboard for a water jacket core for forming the water jacket is formed,
The oil return structure according to any one of claims 1 to 3, wherein the recess is formed using a plug that closes the core hole. The oil return structure according to claim 5, wherein the recess is formed by the core hole and a plug that closes the core hole.

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