BLOW-BY GAS OIL SEPARATOR

Abstract

A blow-by gas oil separator that can prevent oil discharged into an oil receiving chamber from flowing backward into a cyclone includes: multiple cyclones to which blow-by gas of an internal combustion engine is supplied, each cyclone including, in a lower portion, an oil discharge opening that separates out and discharges oil mist contained in the blow-by gas, and including, in an upper portion, a blow-by gas outlet that allows the blow-by gas to flow out after oil separation; an oil receiving portion opposing the oil discharge openings of the cyclones; a blow-by gas circulation portion in communication with the blow-by gas outlets of the cyclones, and is connected to an air intake passage of the internal combustion engine via a circulation valve; and partition walls in an oil receiving chamber formed by the cyclones and the oil receiving portion to separate adjacent oil discharge openings from each other.

Description

TECHNICAL FIELD

The present invention relates to a blow-by gas oil separator that includes multiple cyclones capable of separating out oil mist contained in blow-by gas.

BACKGROUND ART

In an internal combustion engine such as an engine for an automobile, blow-by gas that has leaked from the combustion chamber into the crankcase is returned to the air intake passage and caused to undergo combustion again in the combustion chamber.

Blow-by gas contains oil mist, which is formed by engine oil or the like that has been dispersed as microscopic particles, and therefore such oil mist needs to be separated from the blow-by gas before being caused to undergo combustion in the combustion chamber.

The aforementioned blow-by gas oil separator is used in such an application.

A conventional blow-by gas oil separator disclosed in Patent Document 1 includes: multiple cyclones that are supplied with blow-by gas of an internal combustion engine, each including, in a lower portion, an oil discharge opening that separates out and discharges oil mist contained in the blow-by gas, and including, in an upper portion, a blow-by gas outlet that allows the blow-by gas to flow out after oil separation; an oil receiving portion that opposes the oil discharge openings of the cyclones; a blow-by gas circulation portion that is in communication with the blow-by gas outlets of the cyclones, and is connected to the air intake passage of the internal combustion engine via a circulation valve; and an oil receiving chamber formed by the cyclones and the oil receiving portion.

Due to negative pressure generated in the air intake passage of the internal combustion engine, blow-by gas is suctioned in and supplied to the cyclones, and then after oil separation, the blow-by gas is suctioned into the blow-by gas circulation portion through the blow-by gas outlets. The oil that was separated out by the cyclones is discharged to the oil receiving portion through the oil discharge openings due to its own weight.

The oil discharge openings provided in the lower portions of the cyclones and the blow-by gas outlets provided in the upper portions of the cyclones are in communication with each other via the interiors of the cyclones. Accordingly, negative pressure generated in the air intake passage is introduced to the oil discharge openings as well.

The magnitude of the negative pressure introduced to an oil discharge opening increases the closer the blow-by gas outlet in communication with that oil discharge opening is located to the circulation valve.

PRIOR ART DOCUMENTS

Patent Documents

Patent Document 1: JP 2009-221857A

SUMMARY OF INVENTION

Technical Problem

With the conventional blow-by gas oil separator, there is a risk that oil in the form of droplets or the like that was discharged into the oil receiving chamber is suctioned through an oil discharge opening that is near the circulation valve and is subjected to high negative pressure, and flows backward into a cyclone.

If oil flows backward into a cyclone, that oil is suctioned into the blow-by gas circulation portion through the blow-by gas outlet, and can easily flow into the air intake passage through the circulation valve.

The present invention was achieved in light of the above-described circumstances, and an object thereof is to provide a blow-by gas oil separator that can prevent oil that was discharged into the oil receiving chamber from flowing backward into a cyclone.

Solution of Problem

A characteristic configuration of a blow-by gas oil separator according to one aspect of the present invention lies in that the blow-by gas oil separator includes: a plurality of cyclones to which blow-by gas of an internal combustion engine is supplied, each of the cyclones including, in a lower portion, an oil discharge opening that separates out and discharges oil mist contained in the blow-by gas, and including, in an upper portion, a blow-by gas outlet that allows the blow-by gas to flow out after oil separation; an oil receiving portion that opposes the oil discharge openings of the plurality of cyclones; a blow-by gas circulation portion that is in communication with the blow-by gas outlets of the plurality of cyclones, and is connected to an air intake passage of the internal combustion engine via a circulation valve; and partition walls that are provided in an oil receiving chamber formed by the plurality of cyclones and the oil receiving portion, and separate adjacent oil discharge openings from each other.

In the blow-by gas oil separator having this configuration, the partition walls that separate adjacent oil discharge openings from each other are provided on the oil receiving chamber.

For this reason, oil in the form of droplets or the like that was discharged from the oil discharge openings into the oil receiving portion can be prevented from flowing backward into a cyclone through a different oil discharge opening.

Another characteristic configuration of one aspect of the present invention lies in that the partition walls are provided so as to be integrated on a cyclone side, and a gap is formed between lower ends of the partition walls and the oil receiving portion.

According to this configuration, the relative positions of the partition walls and the cyclones can be easily determined with favorable precision.

Also, it is easy to cause discharged oil to flow through the gap between the lower ends of the partition walls and the oil receiving portion, toward a drain hole or the like formed in the oil receiving portion, for example.

Another characteristic configuration of one aspect of the present invention lies in that the blow-by gas circulation portion includes an inner bottom portion that is lower with increasing distance from the circulation valve.

According to this configuration, even if oil that has flowed backward into a cyclone is suctioned into the blow-by gas circulation portion and accumulates, it is possible to cause that oil to flow toward the side distant from the circulation valve and prevent that oil from flowing into the air intake passage through the circulation valve.

Another characteristic configuration of one aspect of the present invention lies in that the blow-by gas circulation portion has an inner bottom portion in which the blow-by gas outlets are each formed, and the inner bottom portion is provided with an oil channel along which oil can flow so as to move away from the circulation valve while avoiding the blow-by gas outlets, and a communication channel that can put a terminal side of the oil channel in communication with the oil receiving chamber.

In this configuration as well, even if oil that has flowed backward into a cyclone is suctioned into the blow-by gas circulation portion and accumulates, it is possible to cause that oil to flow so as to move away from the circulation valve and prevent that oil from flowing into the air intake passage through the circulation valve.

Also, in the case where the blow-by gas circulation portion has the inner bottom portion in which the blow-by gas outlets are each formed, as in this configuration, there is a risk that oil in the process of flowing along the oil channel flows from a blow-by gas outlet into a cyclone, thus reducing the oil separation capability.

For this reason, the blow-by gas oil separator according to this configuration is provided with the oil channel along which oil suctioned into the blow-by gas circulation portion can flow while avoiding the blow-by gas outlets, and the communication channel that can put the terminal side of the oil channel into communication with the oil receiving chamber.

Accordingly, oil in the process of flowing along the oil channel can be caused to flow from the communication channel into the oil receiving chamber, without flowing into cyclones, and it is possible to prevent a reduction in the oil separation capability of the cyclones.

Another characteristic configuration of one aspect of the present invention lies in that the inner bottom portion is provided with a projection portion that separates one end side of the oil channel in a width direction from a blow-by gas outlet side.

According to this configuration, when oil flows along the oil channel, the spread of the oil in the channel width direction can be restricted by the projection portion, and oil in the processing of flowing along the oil channel toward the communication channel can be reliably prevented from flowing into cyclones.

Another characteristic configuration of one aspect of the present invention lies in that a receding portion is formed at a terminal side of the oil channel, the receding portion is deeper than a channel portion on an upstream side of the terminal side of the oil channel, and the communication channel is open at a bottom portion of the receding portion.

According to this configuration, it is possible to cause oil flowing along the oil channel to flow into the receding portion at the terminal side of the oil channel, and cause the oil to flow from the communication channel open at the bottom portion of the receding portion into the oil receiving chamber.

The receding portion is deeper than the channel portion on the upstream side thereof, and therefore there is little risk that oil that has accumulated in the receding portion is suctioned toward the circulation valve.

Even in the case where the orientation relative to the horizontal direction is likely to vary, as with an oil separator for an automobile in particular, it is possible to reliably prevent oil from flowing into cyclones.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an oil separator.

FIG. 2 is a plan view of the oil separator.

FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2.

FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3 seen in a direction indicated by arrows.

FIG. 5 is a cross-sectional view taken along line V-V in FIG. 3 seen in a direction indicated by arrows.

FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 3 seen in a direction indicated by arrows.

FIG. 7 is a vertical cross-sectional diagram showing an oil separator according to a second embodiment.

FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 7 seen in a direction indicated by arrows.

FIG. 9 is a vertical cross-sectional diagram showing an oil separator according to a third embodiment.

FIG. 10 is a vertical cross-sectional diagram showing an oil separator according to a fourth embodiment.

FIG. 11 is a vertical cross-sectional diagram showing an oil separator according to a fifth embodiment.

FIG. 12 is a cross-sectional view taken along line XII-XII in FIG. 11 seen in a direction indicated by arrows.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described below with reference to the drawings.

First Embodiment

FIGS. 1 to 6 show a cyclone-type blow-by gas oil separator according to the present invention, which is for mounting inside a cylinder head cover (not shown) or the like of an internal combustion engine such as an engine for an automobile.

In the oil separator A, internal combustion engine blow-by gas that flows from the crankcase (not shown) into the cylinder head cover is supplied to cyclones B by being suctioned by negative pressure generated in an air intake passage (not shown) in accompaniment with an air intake operation of the internal combustion engine, and oil mist contained in the blow-by gas is removed by centrifugal separation.

After the oil mist has been removed, the blow-by gas is returned to the air intake passage of the internal combustion engine via a circulation valve (not shown) such as a PCV valve (Positive Crankcase Ventilation valve), and then subjected to combustion again in the combustion chamber.

As shown in FIG. 3, the oil separator A includes, inside a resin housing 1, multiple (four in the present embodiment) cyclones B to which blow-by gas is supplied, an oil receiving chamber 2 that receives oil separated out by the cyclones B, and a blow-by gas circulation chamber (blow-by gas circulation portion) 3 that is connected to the air intake passage of the internal combustion engine via the circulation valve.

The cyclones B each include, in a lower portion, an oil discharge opening 4 that separates out oil mist contained in blow-by gas and discharges the oil mist using the weight thereof, and include, in an upper portion, a blow-by gas outlet 5 that allows the blow-by gas to flow out after oil separation.

The oil receiving chamber 2 is formed between the four cyclones B and an oil receiving portion 6 that opposes the oil discharge openings 4, and is configured so as to collect oil that is discharged from the oil discharge openings 4, and return the oil to the inside of the engine through a drain pipe 7.

The blow-by gas outlets 5 are each in communication with the blow-by gas circulation chamber 3, and are configured so as to collect the blow-by gas flowing in through the blow-by gas outlets 5 after oil separation, and return the blow-by gas from a gas discharge pipe 8 to the air intake passage of the internal combustion engine via the circulation valve.

As shown in FIGS. 1 to 3, the housing 1 is assembled by fitting a lower case 1a and an intermediate case 1b to an upper case 1c and a lid case 1d in the vertical direction.

The space formed between the lower case 1a and the intermediate case 1b is partitioned into the oil receiving chamber 2 and a gas introduction chamber 9 into which blow-by gas inside the cylinder head cover is introduced through a gas introducing opening 9a.

As shown in FIG. 5, a straightening chamber 10, which straightens the flow of blow-by gas before flowing into the cyclones B, and a blow-by gas inflow passage 10a, which allows blow-by gas to flow from the gas introduction chamber 9 into the straightening chamber 10, are formed between the intermediate case 1b and the upper case 1c.

The space between the upper case 1c and the lid case 1d forms the blow-by gas circulation chamber 3 as shown in FIG. 4.

The drain pipe 7, by which oil collected in the oil receiving chamber 2 is returned to the inside of the engine, is connected to the lower case 1a.

The oil receiving portion 6 is formed by the bottom plate portion of the lower case 1a, and is inclined such that oil flows toward the drain pipe 7 due to its own weight.

As shown in FIGS. 3 and 5, an oil receiving chamber upper wall 2a, which separates the straightening chamber 10 and the oil receiving chamber 2 in the vertical direction, and the four cyclones B that penetrate the oil receiving chamber upper wall 2a in the vertical direction are formed so as to be integrated in the intermediate case 1b.

As shown in FIGS. 3 and 5, the cyclones B each include a conical tube wall portion 12 whose inner diameter decreases as it extends downward, and a circular tube wall portion 11 whose inner diameter is constant and that extends upward from the upper edge of the conical tube wall portion 12, and the conical tube wall portion 12 and the circular tube wall portion 11 are integrated about a tube axis X that extends in the vertical direction.

The four cyclones B are arranged side-by-side in a straight line with the positions of their tube axes X at equal intervals in a plan view, and are aligned such that the circular tube wall portions 11 are connected to each other in an integrated manner.

The circular tube wall portions 11 are provided so as to protrude from the oil receiving chamber upper wall 2a into the straightening chamber 10, and a blow-by gas supply opening 11a, which allows blow-by gas in the straightening chamber 10 to flow in from a direction tangential to the inner side of the circular tube wall portion 11, is formed as a slit in each of the circular tube wall portions 11.

The conical tube wall portions 12 are provided so as to protrude from the oil receiving chamber upper wall 2a into the oil receiving chamber 2, and the lower end openings of the conical tube wall portions 12 function as the oil discharge openings 4.

As shown in FIGS. 3 and 4, the upper case 1c includes a distribution chamber lower wall 3a that separates the blow-by gas circulation chamber 3 and the straightening chamber 10 in the vertical direction, and the blow-by gas outlets 5 are formed in the distribution chamber lower wall 3a.

Accordingly, the blow-by gas circulation chamber 3 has an inner bottom portion 16 in which the blow-by gas outlets 5 are each formed. The upper end portions of the circular tube wall portions 11 are fitted into and fixed to the lower surface side of the distribution chamber lower wall 3a.

Circular tube portions 13 that form the blow-by gas outlets 5 are formed so as to be integrated with the lower surface side of the distribution chamber lower wall 3a. The circular tube portions 13 are provided so as to coaxially enter the corresponding cyclones B with a gap in the diameter direction from the inner sides of the circular tube wall portions 11.

The gas discharge pipe 8, which is connected to the air intake passage of the internal combustion engine via the circulation valve, is provided in the lid case 1d.

As shown in FIG. 4, the gas discharge pipe 8 is provided so as to be in communication with the interior of the blow-by gas circulation chamber 3 on one end side in the alignment direction of the blow-by gas outlets 5 (on the side distant from the blow-by gas inflow passage 10a).

The following describes operations of the oil separator A.

Blow-by gas inside the cylinder head cover is introduced into the gas introduction chamber 9 by being suctioned through the gas introducing opening 9a due to negative pressure generated in the air intake passage in accompaniment with an air intake operation of the internal combustion engine.

The blow-by gas introduced into the gas introduction chamber 9 flows into the straightening chamber 10 through the blow-by gas inflow passage 10a, and then flows from the blow-by gas supply openings 11 a into the circular tube wall portions 11.

Oil mist contained in the blow-by gas that flowed into the circular tube wall portions 11 undergoes coagulative separation into droplets of oil due to centrifugal force that accompanies circulation about the tube axis (circular tube portions 13) X.

The oil separated out in the form of droplets by the cyclones B then falls through the oil discharge openings 4 into the oil receiving chamber 2 and is collected in the oil receiving portion 6, and is then returned to the inside of the engine through the drain pipe 7.

After the oil mist has been separated out, the blow-by gas is suctioned through the circular tube portions 13 into the blow-by gas circulation chamber 3 via the blow-by gas outlets 5, and then flows back through the gas discharge pipe 8 to the combustion chamber via the air intake passage.

The oil discharge openings 4 provided in the cyclones B are in communication with the blow-by gas outlets 5 inside the cyclones B. For this reason, negative pressure generated in the air intake passage acts on the oil discharge openings 4 as well, and there is a risk that droplets of oil discharged into the oil receiving chamber 2 are suctioned through the oil discharge openings 4, travel inside the cyclones B, and flow backward into the blow-by gas circulation chamber 3.

The magnitude of the negative pressure acting on an oil discharge opening 4 of a cyclone B increases the closer the blow-by gas outlet 5 in communication with the oil discharge opening 4 is arranged to the entrance of the gas discharge pipe 8 (the downstream side in the direction of the flow of blow-by gas toward the air intake passage).

For this reason, droplets of oil discharged from one oil discharge opening 4 into the oil receiving chamber 2 need to be prevented from being suctioned through an oil discharge opening 4 different from that one oil discharge opening 4, that is to say, through the oil discharge opening 4 of a cyclone B that is arranged farther downstream, in the direction of the flow of blow-by gas toward the gas discharge pipe 8, than the cyclone B that includes that one oil discharge opening 4.

In order to prevent this suctioning of oil, band plate-shaped partition walls 14 are provided in order to, by separating adjacent oil discharge openings 4 from each other, prevent the suctioning of droplets of oil through oil discharge openings 4 on which high negative pressure easily acts.

The partition walls 14 are provided on the cyclone B side, that is to say, so as to be integrated with the intermediate case 1b, between respective pairs of adjacent conical tube wall portions 12, and extend in a straight line so as to traverse the interior of the oil receiving chamber 2 in the direction orthogonal to the alignment direction of the cyclones B.

A slit-shaped gap 15 that extends along the oil receiving surface of the oil receiving portion 6 is formed between the lower ends of the partition walls 14 and the oil receiving portion 6.

If oil that has been discharged to the oil receiving chamber 2 is suctioned through an oil discharge opening 4 and flows backward into a cyclone B, that oil flows into the blow-by gas circulation chamber 3 along with blow-by gas and accumulates.

Also, if oil mist is not completely separated out by the cyclones B and remains in blow-by gas that is suctioned into the blow-by gas circulation chamber 3, such oil mist coagulates and remains inside the blow-by gas circulation chamber 3.

For this reason, the blow-by gas circulation chamber 3 is provided in an orientation in which the upper surface of the distribution chamber lower wall 3a, which forms the inner bottom portion 16 of the blow-by gas circulation chamber 3, is inclined relative to the horizontal direction so as to become lower with increasing distance from the circulation valve, that is to say with increasing distance from the entrance of the gas discharge pipe 8, such that oil that has accumulated therein can be discharged to the oil receiving chamber 2.

As shown in FIG. 4, the inner bottom portion 16 is provided with an oil channel 17 along which oil can flow due to its own weight so as to move away from the circulation valve, that is to say move away from the entrance of the gas discharge pipe 8, while avoiding the blow-by gas outlets 5. A communication channel 18, which can put the oil channel 17 into communication with the oil receiving chamber 2, is open at the terminal side of the oil channel 17. The communication channel 18 is formed by one of the circular tube portions 13.

The oil channel 17 is formed as a channel that is sandwiched between a side wall portion 19 of the upper case 1c that surrounds the blow-by gas circulation chamber 3 and a projection portion 20 that projects from the inner bottom portion 16 and extends along the alignment direction of the blow-by gas outlets 5 at a position separated from them.

The projection portion 20 is provided so as to extend in a continuous manner from a position in the vicinity of and below the entrance of the gas discharge pipe 8 to the blow-by gas outlet 5 located the farthest from the entrance of the gas discharge pipe 8, and separates one end side of the oil channel 17 in the width direction from the blow-by gas outlet 5 side.

Among the circular tube portions 13 of the cyclones B, the communication channel 18 is formed by the circular tube portion 13 that is in communication with the blow-by gas outlet 5 at the farthest position from the circulation valve, that is to say the farthest position from the entrance of the gas discharge pipe 8.

Accordingly, oil that has flowed from the oil channel 17 into the communication channel 18 travels through the interior of the cyclone B and is discharged from the oil discharge opening 4 into the oil receiving chamber 2.

Second Embodiment

FIGS. 7 and 8 show another embodiment of the present invention.

In the present embodiment, in order to prevent droplets of oil discharged from one oil discharge opening 4 into the oil receiving chamber 2 from being suctioned through an oil discharge opening 4 different from that one oil discharge opening 4, tube-shaped partition walls 14 are provided instead of the band plate-shaped partition walls 14 described in the first embodiment. The tube-shaped partition walls 14 extend from the lower end sides of the circular tube wall portions 11 that constitute the cyclones B, in the shape of cylinders that surround the conical tube wall portions 12, and separate adjacent oil discharge openings 4 from each other.

A gap 15 is formed between the lower ends of the tube-shaped partition walls 14 and the oil receiving portion 6, so as to separate the lower ends of the tube-shaped partition walls 14 from the oil receiving portion 6.

Other aspects of the configuration are the same as in the first embodiment.

Third Embodiment

FIG. 9 shows another embodiment of the present invention.

In the present embodiment, in order to prevent droplets of oil discharged from one oil discharge opening 4 into the oil receiving chamber 2 from being suctioned through an oil discharge opening 4 different from that one oil discharge opening 4, ring-shaped partition walls 14 are provided instead of the tube-shaped partition walls 14 described in the second embodiment. The ring-shaped partition walls 14 are obtained by extending the lower ends of the conical tube wall portions 12 that constitute the cyclones B toward the oil receiving portion 6, and separate adjacent oil discharge openings 4 from each other.

Other aspects of the configuration are the same as in the second embodiment.

Fourth Embodiment

FIG. 10 shows another embodiment of the present invention.

In the present embodiment, in order to prevent droplets of oil discharged from one oil discharge opening 4 into the oil receiving chamber 2 from being suctioned through an oil discharge opening 4 different from that one oil discharge opening 4, band plate-shaped partition walls 14 are provided instead of the partition walls 14 described in the first embodiment that are provided so as to be integrated with the intermediate case 1b. The band plate-shaped partition walls 14 are provided so as to be integrated with the lower case 1 a that forms the oil receiving chamber 2, and separate adjacent oil discharge openings 4 from each other.

The partition walls 14 are provided between respective pairs of adjacent conical tube wall portions 12, and extend in a straight line so as to traverse the interior of the oil receiving chamber 2 in the direction orthogonal to the alignment direction of the cyclones B.

Arc-shaped through-holes 14a, for example, are formed in portions of the partition walls 14 that rise up from the oil receiving portion 6, so as to not hinder the flow of oil toward the drain pipe 7.

Other aspects of the configuration are the same as in the first embodiment.

Fifth Embodiment

FIGS. 11 and 12 show another embodiment of the present invention.

In the present embodiment, a circular receding portion 21 is formed at the terminal side of the oil channel 17 illustrated in the first embodiment, and is deeper than the channel portion on the upstream side of the terminal side of the oil channel 17.

Among the circular tube portions 13 of the cyclones B, the receding portion 21 is formed so as to be coaxial with the circular tube portion 13 that is in communication with the blow-by gas outlet 5 at the farthest position from the circulation valve, that is to say the farthest position from the entrance of the gas discharge pipe 8, and the blow-by gas outlet 5 that forms the communication channel 18 is formed in the bottom portion of the receding portion 21.

Other aspects of the configuration are the same as in the first embodiment.

Other Embodiments

1. The oil separator according to the present invention may be provided outside of the cylinder head cover.

2. The oil separator according to the present invention can be mounted in various types of internal combustion engines other than an engine for an automobile.

REFERENCE SIGNS LIST

2: oil receiving chamber

3: blow-by gas circulation portion (blow-by gas circulation chamber)

4: oil discharge opening

5: blow-by gas outlet

6: oil receiving portion

14: partition wall

15: gap

16: inner bottom portion

17: oil channel

18: communication channel

20: projection portion

21: receding portion

B: cyclone

Claims

1. (canceled)

2. (canceled)

3. (canceled)

4. (canceled)

5. (canceled)

6. (canceled)

7. A blow-by gas oil separator comprising:

a plurality of cyclones to which blow-by gas of an internal combustion engine is supplied, each of the cyclones including, in a lower portion, an oil discharge opening that separates out and discharges oil mist contained in the blow-by gas, and including, in an upper portion, a blow-by gas outlet that allows the blow-by gas to flow out after oil separation;

an oil receiving portion that opposes the oil discharge openings of the plurality of cyclones;

a blow-by gas circulation portion that is in communication with the blow-by gas outlets of the plurality of cyclones, and is connected to an air intake passage of the internal combustion engine via a circulation valve; and

partition walls that are provided in an oil receiving chamber formed by the plurality of cyclones and the oil receiving portion, and separate adjacent oil discharge openings from each other,

wherein the partition walls are provided so as to be integrated with the cyclones, and a gap is formed between lower ends of the partition walls and the oil receiving portion.

8. The blow-by gas oil separator according to claim 7, wherein the blow-by gas circulation portion includes an inner bottom portion that is lower with increasing distance from the circulation valve.

9. The blow-by gas oil separator according to claim 7, wherein

the blow-by gas circulation portion has an inner bottom portion in which the blow-by gas outlets are each formed, and

the inner bottom portion is provided with an oil channel along which oil can flow so as to move away from the circulation valve while avoiding the blow-by gas outlets, and a communication channel that can put a terminal side of the oil channel in communication with the oil receiving chamber.

10. The blow-by gas oil separator according to claim 9, wherein the inner bottom portion is provided with a projection portion that separates one end side of the oil channel in a width direction from a blow-by gas outlet side.

11. The blow-by gas oil separator according to claim 9, wherein a receding portion is formed at a terminal side of the oil channel, the receding portion is deeper than a channel portion on an upstream side of the terminal side of the oil channel, and the communication channel is open at a bottom portion of the receding portion.