Blow-by gas passage structure

A blow-by gas passage structure is provided inside a separator chamber that is formed between a cylinder head cover and a baffle plate joined to the cylinder head cover by vibration welding. A first rib is provided on the opposite surface of one member of the cylinder head cover and the baffle plate, while a second rib is provided on the opposite surface of the other member, at positions upstream of the first rib in the flow of the blow-by gas and adjacent a gap formed between the distal end of the first rib and the opposite surface of the other member. The second rib has a height that is equal to or larger than the height of the gap so as to prevent passing of the blow-by gas through the gap.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119 of Japanese Application No. 2015-99441 filed on May 14, 2015 and Japanese Application No. 2016-47600 filed on Mar. 10, 2016, the disclosure of which is expressly incorporated by reference herein in its entirety.

BACKGROUND

1. Technical Field

The present invention relates to a blow-by gas passage structure, and more particularly to a blow-by gas passage structure provided inside a separator chamber that is formed between a cylinder head cover and a baffle plate joined to the cylinder head cover by vibration welding.

2. Background Art

As a conventional oil mist separator, one provided inside a separator chamber that is formed between a cylinder head cover and a baffle plate joined to the cylinder head cover by vibration welding is commonly known (see, for example, JP2011-58433A). In this conventional oil mist separator, for example, as shown inFIG. 5andFIG. 6, path-bending ribs111stand on the surface(s) of the cylinder head cover102and/or baffle plate103to cause the flow of blow-by gas to bend (meander) in a planar direction inside the separator chamber S. The flow of blow-by gas introduced from an inlet105into the separator chamber S is bent by path-bending ribs111, and the oil components in the blow-by gas are caught through gravity sedimentation and collision. After that, the blow-by gas, from which the oil components have been separated, is discharged from the separator chamber S by a PCV valve107provided to an outlet106, and transferred to the combustion chamber of the engine via an intake manifold or the like.

In the conventional oil mist separator described above, there is a gap g between the distal end of the path-bending ribs111and the surface of the opposing member (cylinder head cover102or baffle plate103) in order to avoid interference (i.e., vibration welding) therebetween. This is because interference between the path-bending ribs111and the surface of the opposing member will cause the following problems. For example, burrs (foreign matter) may form after the vibration welding, or flash trap design for the vibration welding may become difficult. If the path-bending ribs111are high and have low rigidity, the path-bending ribs111may wobble largely by the vibration during the vibration welding, which may impede the heating of the resin and result in a weld failure.

Since a gap g is formed between the distal end of the path-bending ribs111and the surface of the opposing member for avoiding interference in the conventional oil mist separator described above, part of the blow-by gas passes through the gap g, thus creating a short-cut flow path119. Therefore, the flow path120of the blow-by gas may not form as designed and intended, and the flow of blow-by gas may not be bent sufficiently, with a result that the efficiency of separating oil components in the blow-by gas is lowered.

Moreover, in the conventional oil mist separator described above, when the negative pressure inside the separator chamber S is high and when the PCV valve107(outlet106) and the oil drop hole108are disposed close to each other, the blow-by gas is sucked into the separator chamber S through the oil drop hole108and flows toward the PCV valve107. Therefore, for example, a blocking rib that blocks the flow of blow-by gas from the oil drop hole108toward the outlet106could be provided on the surface of the cylinder head cover102or the baffle plate103. Even such a blocking rib would have to be formed with a gap g for avoiding interference between its distal end and the surface of the opposing member, similarly to the path-bending ribs111described above. Part of the blow-by gas would then pass through the gap g and thereby a short-cut flow path would be created. As a result, the effect of blocking the blow-by gas would be lowered, and the efficiency of separating oil components in the blow-by gas would also be lowered.

SUMMARY

The embodiments of the present invention were made in view of the circumstances described above, with an object to provide a blow-by gas passage structure that can improve the efficiency of separating oil components contained in the blow-by gas.

One aspect of the present embodiments provides a blow-by gas passage structure provided inside a separator chamber that is formed between a cylinder head cover and a baffle plate joined to the cylinder head cover by vibration welding to form a passage for blow-by gas introduced into the separator chamber for separation of oil components, wherein the cylinder head cover and the baffle plate include respective opposite surfaces that face each other in an up and down direction of the cylinder head cover, the opposite surface of either one of the cylinder head cover and the baffle plate is provided with a first rib, and the opposite surface of the other member is provided with a second rib at a position which is in the upstream of the first rib in a flow of the blow-by gas and which is adjacent to a gap formed between a distal end of the first rib and the opposite surface of the other member, and the second rib has a height that is equal to or greater than a height of the gap so as to prevent passing of the blow-by gas through the gap.

In a further aspect, the first rib and the second rib may be path-bending ribs provided for causing the flow of the blow-by gas to bend along a planar direction of the cylinder head cover inside the separator chamber.

In a further aspect, the first and second path-bending ribs may be disposed opposite an inlet for introducing the blow-by gas into the separator chamber.

In a further aspect, the first rib and the second rib may be blocking ribs provided for blocking a flow of blow-by gas traveling from an oil drop hole for discharging separated oil components from the separator chamber toward an outlet through which the blow-by gas is discharged from the separator chamber.

In a further aspect, the second rib may include an inclined surface that separates from the gap in the up and down direction as it approaches the first rib.

In a further aspect, the first rib and the second rib may be disposed such as not to interfere with each other when the cylinder head cover and the baffle plate are joined together by vibration welding.

In a further aspect, the first rib and the second rib adjacent to each other may be distanced from each other by 1 to 10 mm.

In the blow-by gas passage structure of this embodiment, the cylinder head cover and the baffle plate include respective opposite surfaces that face each other in an up and down direction of the cylinder head cover. The opposite surface of one member of the cylinder head cover and the baffle plate is provided with a first rib, while the opposite surface of the other member is provided with a second rib at a position upstream of the first rib in a flow of the blow-by gas and adjacent a gap formed between a distal end of the first rib and the opposite surface of the other member. The second rib has a height that is equal to or larger than the height of the gap so as to prevent passing of the blow-by gas through the gap. Thereby, passing of the blow-by gas through the gap is prevented by the first rib and the second rib. As a result, the efficiency of separating oil components contained in the blow-by gas can be improved.

When the first rib and the second rib are provided for bending the gas path, the flow of blow-by gas is bent in the planar direction of the cylinder head cover inside the separator chamber by these first and second path-bending ribs, so that the oil components in the blow-by gas are separated from the gas. Since passing of the blow-by gas through the gaps is prevented by the first and second path-bending ribs, a flow path of blow-by gas is formed as designed and intended, and the flow of blow-by gas can be bent sufficiently.

When the first and second path-bending ribs are disposed opposite the inlet, the oil components in the blow-by gas will be effectively separated, since the blow-by gas collides the first and second path-bending ribs with a high flow rate when it is introduced from the inlet into the separator chamber. Furthermore, passing of the blow-by gas with a high flow rate through the gaps is prevented by the first and second path-bending ribs.

When the first rib and the second rib are provided for blocking the gas, the flow of blow-by gas that travels from the oil drop hole toward the outlet inside the separator chamber will be blocked by the first and second blocking ribs. Also, since the first and second blocking ribs prevent passing of the blow-by gas through the gaps, the effect of blocking the blow-by gas is enhanced.

When the second rib includes an inclined surface, the blow-by gas will be guided by the inclined surface of the second rib to move away from the gap in the up and down direction. Therefore, passing of the blow-by gas through the gaps can be prevented more reliably.

Furthermore, when the first rib and the second rib are disposed such as not to interfere with each other when the cylinder head cover and the baffle plate are joined together by vibration welding, no burrs will form in the vibration welding on the first and second ribs.

Moreover, when the first rib and the second rib adjacent thereto are distanced from each other by 1 to 10 mm, passing of the blow-by gas through the gaps can be prevented effectively.

DETAILED DESCRIPTION

The blow-by gas passage structure according to this embodiment is a blow-by gas passage structure (1,1′) provided inside a separator chamber (S) that is formed between a cylinder head cover (2) and a baffle plate (3) joined to the cylinder head cover by vibration welding, for constituting a passage for blow-by gas introduced into the separator chamber for separation of oil components (see, for example,FIGS. 1 to 4). The cylinder head cover (2) and the baffle plate (3) include respective opposite surfaces (2a,3a) that face each other in an up and down direction (P) of the cylinder head cover. First ribs (11a,12a,13a,23a) are provided on the opposite surface of one member of the cylinder head cover and the baffle plate, while second ribs (11b,12b,13b,23b) are provided on the opposite surface of the other member, at positions upstream of the first ribs in the flow of the blow-by gas and adjacent a gap (g) formed between the distal ends of the first ribs and the opposite surface of the other member. The second ribs (11b,12b,13b,23b) have a height that is equal to or larger than the height of the gap (g) so as to prevent passing of the blow-by gas through the gap (g).

As used herein, the term “prevent” is intended to mean prevention of passing of a total amount or a considerable percentage of blow-by gas through the gap. For example, the first ribs and second ribs can prevent 80% or more of a total flow amount of the blow-by gas introduced into the separator chamber from passing through the gap. The distance between a first rib and a second rib (d1; seeFIG. 2andFIG. 4) can be set as appropriate, as long as the ribs do not interfere with each other when the cylinder head cover and the baffle plate are joined by vibration welding, and as long as passing of blow-by gas through the gap can be prevented. The distance between adjacent ribs (d1) can be, for example, 1 to 10 mm (preferably 1 to 5 mm, and more preferably 2 to 3 mm). In the case with the embodiment described above, the cylinder head cover (2) may be formed in a box-like shape with the bottom side open, for example, and the baffle plate (3) may be joined to the cylinder head cover such as to close the bottom side.

The blow-by gas passage structure according to this embodiment may be formed to include, for example, first ribs (11a,12a,13a) and second ribs (11b,12b,13b) for bending the gas path (see, for example,FIGS. 1 to 4) to cause the flow of blow-by gas to bend along a planar direction of the cylinder head cover (2) inside the separator chamber (S).

In the case with the embodiment described above, the first rib (11a) and the second rib (11b) for bending the gas path may be disposed opposite an inlet (5) for introducing the blow-by gas into the separator chamber (S) (see, for example,FIG. 2). In this case, for example, a pipe-like inlet (5) may be formed to the cylinder head cover (2) such as to open into the separator chamber (S) sideways at one end, while the first rib (11a) and the second rib (11b) for bending the gas path may be disposed opposite the opening at one end of the inlet.

The blow-by gas passage structure according to this embodiment may be formed to include, for example, a first rib (23a) and a second rib (23b) for blocking the flow of blow-by gas (see, for example,FIGS. 3 and 4) to block the flow of blow-by gas that travels from an oil drop hole (8) for discharging separated oil components from the separator chamber (S) toward an outlet (6) through which the blow-by gas is discharged from the separator chamber (S).

The blow-by gas passage structure according to this embodiment may be formed to include, for example, the second rib (11b) with an inclined surface (16) that separates from the gap in the up and down direction as it approaches the first rib (11a) (see, for example,FIG. 2).

The parenthesized reference numerals of various elements in the embodiments described above indicate the corresponding relationships with specific elements mentioned in embodiments to be described later.

EMBODIMENTS

Hereinafter, the present invention will be explained in specific terms through description of embodiments with reference to the drawings.

(1) Configuration of Blow-by Gas Passage Structure

The blow-by gas passage structure1according to this embodiment is provided inside a separator chamber S that is formed between a cylinder head cover2and a baffle plate3, as shown inFIGS. 1 and 2. This blow-by gas passage structure1constitutes a passage for blow-by gas introduced into the separator chamber S.

The cylinder head cover2is made of a plastic material and formed in a box-like shape with its bottom side open. The baffle plate3is made of a plastic material and joined to the cylinder head cover2by vibration welding along a weld joint4such as to close the bottom side of the cylinder head cover. These cylinder head cover2and baffle plate3include respective opposite surfaces2aand3afacing each other in an up and down direction P of the cylinder head cover2. A planar direction substantially orthogonal to the up and down direction P of the cylinder head cover2will be referred to as the planar direction of the cylinder head cover2.

A substantially L-shaped pipe-like inlet5is provided to the cylinder head cover2for introducing the blow-by gas generated in the engine into the separator chamber S. Also, an outlet6for discharging the blow-by gas from the separator chamber S is provided to the cylinder head cover2. A PCV (Positive Crankcase Ventilation) valve7is mounted to the outlet6for controlling the discharge amount of the blow-by gas. The baffle plate3is formed with an oil drop hole8for returning the oil caught and collected in the separator chamber S back to the engine.

The blow-by gas passage structure1includes the first ribs11a,12a, and13a, and the second ribs11b,12b, and13bfor bending the gas path, and path-bending ribs14. The first ribs11a,12a, and13aand the second ribs11b,12b, and13bfor bending the gas path are ribs that cause the flow of blow-by gas inside the separator chamber S to bend (meander) along the planar direction of the cylinder head cover2. The path-bending ribs14are ribs that cause the flow of blow-by gas inside the separator chamber S to bend (meander) in the up and down direction P of the cylinder head cover2. As the flow of blow-by gas is bent by means of the ribs, the oil components (oil mist) in the blow-by gas are caught and collected through gravity sedimentation and collision against the ribs.

The first path-bending rib11astands on the opposite surface3a(i.e., bottom surface3a) of the baffle plate3. This first rib11ais formed in a planar shape with its distal end extending to near the opposite surface2a(i.e., top surface2a) of the cylinder head cover2. A gap g of a predetermined height distance is formed between the distal end of the first rib11aand the opposite surface2aof the cylinder head cover2.

The second path-bending rib11bis provided on the opposite surface2aof the cylinder head cover2at a position which is in the upstream of the first rib11ain the flow of the blow-by gas and which is adjacent to the gap g. The distance d1between the first rib11aand the adjacent second rib11bis about 3 mm. The second rib11bis formed in the shape of a protrusion that covers the gap g. The second rib11bhas a height greater than that of the gap g. Namely, the second rib11bfaces the distal end of the first rib11ain the planar direction of the cylinder head cover2such as to overlap it along the up and down direction P of the cylinder head cover2. These first rib11aand second rib11bextend linearly so that they are substantially parallel to each other in the planar direction of the cylinder head cover2.

The first rib11aand second rib11bfor bending the gas path are disposed opposite one end of the inlet5. The second rib11bfurther includes an inclined surface16that separates from the gap g downward as it approaches the first rib11a.

The first path-bending rib12astands on the opposite surface2aof the cylinder head cover2. This first rib12ais formed in a planar shape with its distal end extending to near the opposite surface3aof the baffle plate3. A gap g of a predetermined height distance is formed between the distal end of the first rib12aand the opposite surface3aof the baffle plate3.

The second path-bending rib12bis provided on the opposite surface3aof the baffle plate3at a position which is in the upstream of the first rib12ain the flow of the blow-by gas and which is adjacent to the gap g. The distance d1between the first rib12aand the adjacent second rib12bis about 3 mm. The second rib12bis formed in the shape of a protrusion that covers the gap g. The second rib12bhas a height greater than that of the gap g. Namely, the second rib12bfaces the distal end of the first rib12ain the planar direction of the cylinder head cover2such as to overlap it along the up and down direction P of the cylinder head cover2. These first and second ribs12aand12bextend linearly so that they are substantially parallel to each other in the planar direction of the cylinder head cover2.

The first path-bending rib13astands on the opposite surface2aof the cylinder head cover2. This first rib13ais formed in a planar shape with its distal end extending to a midpoint of the distance between the opposing cylinder head cover2and the baffle plate3. A gap g of a predetermined height distance is formed between the distal end of the first rib13aand the opposite surface3aof the baffle plate3.

The second path-bending rib13bstands on the opposite surface3aof the baffle plate3. This second rib13bis provided at a position which is in the upstream of the first rib13ain the flow of the blow-by gas and which is adjacent to the gap g. The distance d1between the first rib13aand the adjacent second rib13bis about 3 mm. This second rib13bis formed in a planar shape with its distal end extending to a midpoint of the distance between the opposing cylinder head cover2and the baffle plate3. The second rib13bhas a height greater than that of the gap g. Namely, the distal ends of the first rib13aand second rib13bface each other in the planar direction of the cylinder head cover2such as to overlap each other along the up and down direction P of the cylinder head cover2. These first rib13aand second rib13bextend linearly so that they are substantially parallel to each other in the planar direction of the cylinder head cover2.

(2) Operation of the Blow-by Gas Passage Structure

Next, the operation of the blow-by gas passage structure1configured as described above will be explained. The blow-by gas introduced from the inlet5into the separator chamber S is bent along the planar direction of the cylinder head cover2by the first ribs11a,12a, and13aand the second ribs11b,12b, and13bfor bending the gas path, and the oil components in the blow-by gas are caught through gravity sedimentation and collision. Next, as the flow of blow-by gas is bent by the path-bending ribs14in the up and down direction P of the cylinder head cover2, the oil components in the blow-by gas are caught through gravity sedimentation and collision. After that, the blow-by gas, from which the oil components have been sufficiently separated, is discharged from the separator chamber S by the PCV valve7provided to the outlet6, and transferred to the combustion chamber of the engine via an intake manifold. On the other hand, the oil caught and collected in the separator chamber S is returned to the engine via the oil drop hole8.

(3) Effects of the Embodiments

In the blow-by gas passage structure1according to this embodiment, the cylinder head cover2and the baffle plate3include respective opposite surfaces2aand3athat face each other in an up and down direction P of the cylinder head cover2. The opposite surface of one member of the cylinder head cover2and the baffle plate3is provided with the first ribs11a,12a, and13a, while the opposite surface of the other member is provided with the second ribs11b,12b, and13bat a position upstream of the first ribs11a,12a, and13ain a flow of the blow-by gas and adjacent the gap g formed between the distal ends of the first ribs11a,12a, and13aand the opposite surface of the other member. The second ribs11b,12b, and13bhave a height that is equal to or larger than the height of the gap g so as to prevent passing of the blow-by gas through the gap g. Thereby, passing of the blow-by gas through the gap g is prevented by the first ribs11a,12a, and13aand the second ribs11b,12b, and13b. As a result, the efficiency of separating oil components contained in the blow-by gas can be improved. Moreover, the first ribs11a,12a, and13aand the second ribs11b,12b, and13benhance the surface rigidity of the cylinder head cover2and baffle plate3, so that sound reduction and shock resistance are improved.

In this embodiment, the first ribs11a,12a, and13aand second ribs11b,12b, and13bare provided for bending the gas path. Accordingly, the flow of blow-by gas is bent in the planar direction of the cylinder head cover2inside the separator chamber S by the first path-bending ribs11a,12a, and13aand the second path-bending ribs11b,12b, and13b, so that the oil components in the blow-by gas are separated from the gas. Since passing of the blow-by gas through the gaps g is prevented by the first path-bending ribs11a,12a, and13aand the second path-bending ribs11b,12b, and13b, a flow path20of blow-by gas is formed as designed and intended, and the flow of blow-by gas can be bent sufficiently.

In this embodiment, the first path-bending rib11aand the second path-bending rib11bare disposed opposite the inlet5. Accordingly, the oil components in the blow-by gas will be effectively separated, since the blow-by gas collides the first path-bending rib11aand the second path-bending rib11bwith a high flow rate when it is introduced from the inlet5into the separator chamber S. Furthermore, passing of the blow-by gas with a high flow rate through the gaps g is prevented by the first path-bending rib11aand the second path-bending rib11b.

In this embodiment, the second rib11bincludes an inclined surface16. Accordingly, the blow-by gas will be guided by the inclined surface16of the second rib11bto move away from the gap g in the up and down direction. Therefore, passing of the blow-by gas through the gaps g can be prevented more reliably.

Next, a blow-by gas passage structure according to Embodiment 2 will be described. Constituent elements of the blow-by gas passage structure according to Embodiment 2 that are substantially the same as those of the blow-by gas passage structure1according to Embodiment 1 are given the same reference numerals and will not be described again in detail.

(1) Configuration of Blow-by Gas Passage Structure

The blow-by gas passage structure1′ according to this embodiment is provided inside a separator chamber S that is formed between a cylinder head cover2and a baffle plate3, as shown inFIGS. 3 and 4. An oil drop hole8is formed in this baffle plate3near the outlet6(i.e., near the PCV valve7) of the cylinder head cover2.

The blow-by gas passage structure1′ includes first ribs11a,12a, and13a, and the second ribs11b,12b, and13bfor bending the gas path, path-bending ribs14, and a first blocking rib23aand a second blocking rib23b. The first blocking rib23aand the second blocking rib23bare ribs provided for blocking the flow of blow-by gas that travels from the oil drop hole8toward the outlet6inside the separator chamber S.

The first path-bending rib23astands on the opposite surface3a(i.e., bottom surface3a) of the baffle plate3. This first rib23ais formed in a planar shape with its distal end extending to near the opposite surface2a(i.e., top surface2a) of the cylinder head cover2. A gap g of a predetermined height distance is formed between the distal end of the first rib23aand the opposite surface2aof the cylinder head cover2.

The second path-bending rib23bis provided on the opposite surface2aof the cylinder head cover2at a position which is in the upstream of the first rib23ain the flow of the blow-by gas and which is adjacent to the gap g. The distance d1between the first rib23aand the adjacent second rib23bis about 3 mm. The second rib23bis formed in the shape of a protrusion that covers the gap g. The second rib23bhas a height greater than that of the gap g. Namely, the second rib23bfaces the distal end of the first rib23ain the planar direction of the cylinder head cover2such as to overlap it along the up and down direction P of the cylinder head cover2. The first rib23aand the second rib23bextend linearly so that they are substantially parallel to each other in the planar direction of the cylinder head cover2.

(2) Operation and Effects of the Blow-by Gas Passage Structure

The blow-by gas passage structure1′ according to this embodiment operates substantially the same and provides substantially the same effects as the blow-by gas passage structure1of the previously described Embodiment 1. In addition, this embodiment includes the first blocking rib23aand the second blocking rib23b, so that the flow of blow-by gas traveling from the oil drop hole8toward the outlet6inside the separator chamber S is blocked by the first blocking rib23aand the second blocking rib23b. Also, since the first blocking rib23aand the second blocking rib23bprevent passing of the blow-by gas through the gap g, the effect of blocking the blow-by gas is enhanced.

The present invention is not limited to the embodiments described above and may be embodied with various changes made within the scope of the present invention in accordance with the purposes and applications. Namely, while the second ribs11b,12b,13b, and23bhave a greater height than the height of the gap g in Embodiments 1 and 2 described above, the height is not limited to this. For example, the second ribs11b,12b,13b, and23bmay have substantially the same height as that of the gap g.

While one form of the second rib11bprovided with an inclined surface16was shown in Embodiments 1 and 2 described above, the invention is not limited to this form. For example, the inclined surface16may be provided to other second ribs12b,13b, and23b. Since the inlet5of the cylinder head cover2described above is formed by an undercut portion, the demolding direction is oblique, the inclined surface16of the second rib11bcan be formed easily. Furthermore, the second rib11bmay not be formed with the inclined surface16, for example.

In Embodiments 1 and 2 described above, the second ribs11band12bin the form of a protrusion are disposed upstream of the flow of the blow-by gas, while the first ribs11aand12aof a planar shape are disposed downstream. The invention is not limited to this form, and the second rib of a planar shape may be disposed upstream of the flow of blow-by gas while the first rib in the form of a protrusion may be disposed downstream, for example.

The shape, number, and arrangement of various ribs11a,11b,12a,12b,13a,13b,23a, and23bin Embodiments 1 and 2 described above may be selected as appropriate in accordance with the oil separation performance and the shape of the separator chamber S, and so on. While a labyrinth type oil separation structure was shown as an example in the embodiments, the invention is not limited to this. Instead of or in addition to the labyrinth type oil separation structure, for example, other oil separation structures that use a filter, centrifugal force, or gravity may be adopted.

The present invention is widely applied as a technique for forming a blow-by gas passage inside a separator chamber formed in a cylinder head cover of a vehicle such as a car, bus or truck.

The present invention is not limited to the above-described embodiments, and various variations and modifications may be possible without departing from the scope of the present invention.