Head cover for internal combustion engine cylinder head

This application claims priority to Japanese Application 2018-162016 filed on Aug. 30, 2018, the contents of each are hereby incorporated by reference in its entirety.

The present invention relates to a head cover for an internal combustion engine cylinder head.

A silencing device of a head cover for a cylinder head of an internal combustion engine comprising a chamber, and a resonator communicating with an inside of the chamber, in which the resonator is provided with a ventilation hole opened inside the head cover, is known (see Patent Literature 1). In such a constitution, noises generated from an active valve air hole are attenuated inside the head cover by the Helmholtz principle of resonance.

[Patent Literature 1]

Japanese Unexamined Patent Application Laid-Open No. H3-124920

A head cover for an internal combustion engine cylinder head is arranged adjacent to a cylinder head. Normal oil is used for a smooth operation of an actuation component, in the cylinder head, and the oil may be splashed to the head cover by the actuation of the actuation component. In a constitution described in the above-mentioned Patent Literature 1, a ventilation hole is exposed to the oil, so that there is a possibility that an opening area of the ventilation hole is decreased by adhesion of the oil. When the opening area of the ventilation hole is decreased, it becomes difficult to properly obtain an attenuating effect of sound due to the Helmholtz principle of resonance.

Therefore, the present invention is made in view of the above-mentioned problems, and an object of the present invention is to continuously restrain sound emitted from the cylinder head by reducing influences of the oil on a sound attenuating effect by the Helmholtz principle of resonance.

To solve the above-mentioned problems, a head cover covering at least one part of an upper face of a cylinder head of an internal combustion has a chamber formation part for forming a chamber to restrain sound propagating through air from the cylinder head, and the chamber formation part has a partition part for partitioning a chamber from a space on the cylinder head side. The partition part has a convex part projecting into the chamber, and the convex part is provided with a through hole penetrating from the space on the cylinder head side to the chamber.

In this aspect, even if the oil flows to the chamber from the through hole, the oil flows down on a side face of the convex part, so that the oil can be kept from remaining in the through hole. Accordingly, the opening area of the through hole can be avoided from decreasing due to the oil, so as to continuously reduce sound generated by the cylinder head and emitted from a main cover.

The through hole may be provided at an uppermost part of the convex part. In this aspect, the oil can be further kept from remaining in the through hole.

The partition part may have a guide path for guiding the oil flowing to the chamber from the through hole at a lower end of the convex part, and the guide part may be inclined while the head cover is mounted to cover the cylinder head. In this aspect, the oil flowing from the through hole can be properly guided.

The chamber formation part may have a discharge hole for discharging the oil guided to the guide path from the chamber. In this aspect, the oil guided by the guide path can be kept from remaining in the chamber.

The through hole may have a corner part indented outward on an inner face. In this aspect, even when the oil is adhered to the through hole, the oil can be collected to the corner part by surface tension onto the inner face of the through hole and adhered to the corner part, so that an area of a round hole required to restrain sound can be properly secured.

According to the present invention, influences of the oil on an attenuating effect of the sound due to the Helmholtz principle of resonance are reduced, so that the sound generated at a cylinder head and emitted from a main cover can be continuously muffled.

FIG. 1 is a top view of a head cover 10 in a first embodiment.

FIG. 2 is a cross section view along a line A-A of FIG. 1 .

FIG. 3( a ) is an enlarged view of an area B of FIG. 2 , and FIG. 3( b ) is a perspective view of FIG. 3( a ) .

FIG. 4( a ) is a diagram when FIG. 3( a ) is seen from a view point C, and FIG. 4( b ) is a perspective view of FIG. 4( a ) .

FIG. 5 is a diagram showing a bottom part 40 of a concave part of a main cover in a second embodiment.

FIGS. 6( a ) to 6( c ) are diagrams showing variation examples of a through hole provided at a convex part.

FIG. 1 is a top view of a head cover 10 in a first embodiment. The head cover 10 has a main cover 12 and a sub cover 14 . The main cover 12 is formed into a sink-like shape having an almost rectangular outer shape seen from above. The sub cover 14 is formed into a U-shape seen from above, and two straight portions extending parallely are formed longer and wider than another straight portion. Hereinafter, an extension direction of the two straight portions of the sub cover 14 , i.e., a direction of an arrow 16 in FIG. 1 is referred to as a “longitudinal direction”.

FIG. 2 is a cross section view along a line A-A of FIG. 1 . For easy understanding, in FIG. 2 , the cross section view along the line A-A of FIG. 1 is rotated by 90 degrees and shown as horizontally long. The head cover 10 is arranged at an upper part of a cylinder head 20 , so that its opening is oriented to a lower part of the cylinder head 20 . In this manner, the head cover 10 covers at least one part of the upper face of the cylinder head 20 of an internal combustion engine. The head cover 10 is mounted to the cylinder head 20 by a fastening tool such as a bolt inserted in a bolt boss 12 c.

The main cover 12 has a body part 12 a and a concave part 12 b . The body part 12 a almost defines an outer shape of the main cover 12 , and is formed into a sink-like shape having an almost rectangular outer shape seen from above.

The concave part 12 b has an outer shape almost the same as that of the sub cover 14 , when seen from above. That is to say, the concave part 12 b is formed in a U-shape when seen from above, and two straight portions extending parallely are formed longer and wider than another straight portion. The concave part 12 b is formed to be indented downwardly from above at an entire portion of a U-shape, while the main cover 12 is mounted to cover the upper part of the cylinder head 20 . A partition wall 12 e is formed on the main cover 12 . The partition wall 12 e is formed into a plate-like shape, and extends perpendicularly upward from the upper face of the concave part 12 b . The partition wall 12 e extends across an entire area in a longitudinal direction of the main cover 12 .

The sub cover 14 is mounted to the upper face of the main cover 12 by vibration adhesion, to cover the concave part 12 b . The sub cover 14 has a cup-like part 14 a and a partition wall 14 b . The cup-like part 14 a is formed to expand upwardly from below at the entire portion of the U-like shape, while it is mounted to the main cover 1 . The partition wall 14 b is formed into a plate-like shape, and extends perpendicularly downward from the inner face of the cup-like part 14 a . The partition wall 14 b extends across an entire area in a longitudinal direction of the sub cover 14 .

When the sub cover 14 is mounted to the main cover 12 , a lower end of the partition wall 14 b of the sub cover 14 comes into contact with an upper end of a partition wall 12 e of the main cover 12 . Thereby, the cup-like part 14 a and the partition wall 14 b of the sub cover 14 , and the concave part 12 b and the partition wall 12 e of the main cover 12 form a first chamber 22 and a first oil mist separator chamber 24 in one straight portion extending in an extension direction, and forms a second chamber 26 and a second oil mist separator chamber 28 at the other straight portion extending in the extension direction. At one remaining straight portion connecting the two straight portions, the first chamber 22 and the second chamber 26 are connected to each other, and the first oil mist separator chamber 24 and the second oil mist separator chamber 28 are connected to each other. At the remaining straight portion, one set or both sets of the first chamber 22 and the second chamber 26 , and the first oil mist separator chamber 24 and the second oil mist separator chamber 28 may be separated from each other.

Concretely, the cup-like part 14 a of the sub cover 14 functions as a partition part for partitioning the first chamber 22 , the first oil mist separator chamber 24 , the second chamber 26 , and the second oil mist separator chamber 28 from an exterior space above the head cover 10 . The concave part 12 b functions as a partition part for partitioning the first chamber 22 , the first oil mist separator chamber 24 , the second chamber 26 , and the second oil mist separator chamber 28 from a space on the head cover 10 side, i.e., an interior space between the head cover 10 and the cylinder head 20 . The partition wall 14 b of the sub cover 14 and the partition wall 12 e of the main cover 12 functions as a partition part for partitioning the first chamber 22 and the first oil mist separator chamber 24 , and partitioning the second chamber 26 and the second oil mist separator chamber 28 .

The first oil mist separator chamber 24 , and the second oil mist separator chamber 28 re-condense and collect the oil existing in a mist-like form in the interior space of the head cover 10 . The function of the oil mist separator chamber is known, so its explanation is omitted.

The first chamber 22 and the second chamber 26 restrain the sound propagating through air from the cylinder head 20 by the Helmholtz principle of resonance. A technique for attenuating and restraining the sound according to the Helmholtz principle of resonance is well-known, so its explanation is omitted. The cup-like part 14 a and the partition wall 14 b of the sub cover 14 , and the concave part 12 b and the partition wall 12 e of the main cover 12 function as a chamber formation part for forming the first chamber 22 and the second chamber 26 to restrain the sound propagating through the air from the cylinder head 20 .

Also, any one of the cup-like part 14 a of the sub cover 14 and the concave part 12 b of the main cover 12 may not be provided, and one of the main cover 12 and the sub cover 14 may be formed flat. In this case, the first chamber 22 and the second chamber 26 may be formed.

The concave part 12 b of the main cover 12 has a bottom part 12 f The bottom part 12 f functions as a partition part for partitioning the first chamber 22 and the second chamber 26 from the space on the cylinder head 20 side. A through hole is provided at the bottom part 12 f , as described below. The through hole is provided to restrain the sound for propagating through the air from the cylinder head 20 by the Helmholtz principle of resonance.

However, as shown in FIG. 2 , the main cover 12 is arranged adjacent to the cylinder head 20 . The cylinder head 20 has an operation component, and the oil may be spattered to the main cover 12 by an actuation of the actuation component. In the first embodiment, the bottom part 12 f is arranged at a portion where a spattering amount of the oil from the cylinder head 20 is comparatively low. A possibility that the oil is spattered to the bottom part 12 f provided with the through hole still remains. There is a possibility that when the oil is spattered to the bottom part 12 f and an opening area of the through hole is reduced due to the adhesion of the oil, the attenuating effect of the sound by the Helmholtz principle of resonance cannot be properly obtained.

FIG. 3( a ) is an enlarged view of an area B of FIG. 2 , and FIG. 3( b ) is a perspective view of FIG. 3( a ) . The bottom part 12 f has plural convex parts 12 g projecting into the first chamber 22 and the second chamber 26 . Plural through holes 12 k from the space on the cylinder head 20 side to the first chamber 22 and the second chamber 26 are provided at each convex part 12 g.

Each convex part 12 g has a peak face 12 i and four side faces 12 j . The peak face 12 i is an uppermost part of the convex part 12 g , and formed into a horizontal flat shape. The side face 12 j is inclined, so that the width of the convex part 12 g becomes larger to the bottom.

In this manner, the through hole 12 k is provided at the convex part 12 g . Even if the oil flows into the first chamber 22 or the second chamber 26 from the through hole 12 k , the oil flows down on the side face 12 j of the convex part 12 g , so that the oil can be kept from remaining in the through hole 12 k . Accordingly, reduction of the opening area of the through hole 12 k due to the oil can be avoided, so as to continuously reduce the sound generated by the cylinder head 20 and emitted from the main cover 12 . The through hole 12 k is provided at the peak face 12 i of the convex part 12 g . Thereby, the oil can be further kept from remaining in the through hole 12 k.

In the first embodiment, each convex part 12 g extends in a longitudinal direction, and is aligned in a direction vertical to the longitudinal direction. Plural through holes 12 k are aligned on one straight line at the uppermost part of each convex part 12 g . Of course, the shape of the convex part 12 g is not limited to such a shape.

FIG. 4( a ) is a diagram when FIG. 3( a ) is seen from a view point C. FIG. 4( b ) is a perspective view of FIG. 4( a ) . A bottom part 12 f of the main cover 12 has a guide path 12 h . The guide path 12 h is provided at a lower end of the convex part 12 g , and guides the oil flowing into the first chamber 22 and the second chamber 26 from the through hole 12 k . Concretely, the guide path 12 h is inclined downwardly as it goes in directions of an arrow 32 of FIG. 4( a ) and arrows 32 , 34 of FIG. 4( b ) , while the head cover 10 is mounted to cover the cylinder head 20 . Furthermore, the bottom part 12 f of the main cover 12 has a discharge hole 12 m for discharging the oil guided to the guide path 12 h from the chamber. Thereby, the oil flowing into the first chamber 22 or the second chamber 26 from the through hole 12 k can be guided through the guide path 12 h , and properly discharged to outside of the first chamber 22 or the second chamber 26 from the discharge hole 12 m.

FIG. 5 is a diagram showing a bottom part 40 of a concave part of a main cover in a second embodiment. The head cover in the second embodiment is similar to the head cover 10 in the first embodiment, except that the bottom part 40 is formed instead of the bottom part 12 f.

The bottom part 40 has plural convex parts 40 a and guide paths 40 b . In the second embodiment, one through hole 40 e is provided to each of the plural convex parts 40 a . The convex part 40 a has a peak face 40 c and four side faces 40 d . Also, in the second embodiment, the peak face 40 c is an uppermost part of the convex part 40 a , and is formed into a horizontal flat shape. The side face 40 d is inclined, so that the width of the convex part 40 a becomes larger to the bottom. In the second embodiment, the peak face 40 c is formed into an almost square shape, and the side faces 40 d are formed into almost the same trapezoidal shape.

In this manner, one through hole 40 e is provided at each of the plural convex parts 40 a , so that the oil flowing from the through hole 40 e can flow down on the more side faces 40 d . Therefore, the flow of the oil from the through hole 40 e can be promoted, so as to restrain reduction of the opening area of the through hole 40 e due to the oil. It is similar to the first embodiment, that the guide path 40 b is provided at the lower end of the convex part 40 a to guide the oil flowing into the first chamber 22 and the second chamber 26 from the through hole 40 e.

FIG. 6( a ) to FIG. 6( c ) are diagrams showing variation examples of a through hole provided at a convex part. In these variation examples, the through hole provided at the convex part is formed to house a round hole with a diameter required to restrain sound according to the Helmholtz principle of resonance (hereinafter referred to as a “standard hole”), and to have a corner part indented outward on an inner face. The diameter of the standard hole is obtained by a test or analysis according to a size or shape of the first chamber 22 and the second chamber 26 .

In a variation example, as shown in FIG. 6( a ) , the through hole 42 provided at the convex part is formed to house the standard hole 44 and has four corner parts. The four corner parts are formed at a tip of a triangle shape radially extending and tapered in four directions with the standard hole 44 as a center. That is to say, the through hole 42 is formed into a throwing star having four blades.

In another variation example, as shown in FIG. 6( b ) , the through hole 46 provided at the convex part is formed to house the standard hole 44 , and has five corner parts. The five corner parts are formed at a tip of a triangle shape radially extending and tapered in five directions with the standard hole 44 as a center. That is to say, the through hole 46 is formed into a star-like shape.

In further variation example, as shown in FIG. 6( c ) , the through hole 48 provided at the convex part is formed to house the standard hole 44 and have six corner parts. The six corner parts are formed at a tip of a triangle shape radially extending and tapered in six directions with the standard hole 44 as a center. That is to say, the through hole 46 is formed into a six-rayed star-like shape.

In this manner, the through hole has the corner parts. Even when the oil is adhered to the through hole, the oil can be collected to the corner part by surface tension onto the inner face of the through hole and adhered to the corner part, so that the standard hole 44 can be avoided from being blocked by the oil and an area of the standard hole 44 can be properly secured. Therefore, it can be avoided that a sound restraining effect is reduced due to the adhesion of the oil onto the through hole.

In another variation example, the main cover does not have the concave part 12 b and the partition wall 12 e of the main cover in the first embodiment, and has the cup-like part 14 a and the partition wall 14 b of the sub cover 14 , instead. Also, the sub cover has the concave part 12 b and the partition wall 12 e of the main cover 12 in the first embodiment. The sub cover is mounted from the bottom of the main cover, to cover the cup-like part of the main cover. In this aspect, a chamber for restraining sound propagating through the air from the cylinder head 20 can be formed.

The present invention is explained with reference to the embodiments as above, but the present invention is not limited to the above-mentioned embodiments, and includes proper combinations or replacements of constitutions in the embodiments. Also, it is possible to make variations such as proper alterations of the combination or processing order and various design changes in the embodiment based on a knowledge of those skilled in the art, and the embodiments with such variations may be included in the scope of the present invention.