JP7613309B2 - Cover drainage structure - Google Patents

Description

The present invention relates to a drainage structure for a cover.

Liquids can accumulate in components mounted on the upper part of the engine structure, which can lead to corrosion and deterioration of the components.
Therefore, for example, in the device described in Patent Document 1, a drain hole is provided in the cam cap plate, which is a structure assembled to the top of the cylinder head, in order to drain liquid that accumulates on the upper surface of the cam cap plate.

Japanese Patent Application Publication No. 10-299569

However, a cover such as a head cover is attached to the top of the engine structure. If this cover has a split structure that is divided into a first cover with an opening and a second cover that is placed below the opening, the following problems may occur.

In other words, because the second cover is a component that constitutes the bottom surface of the recess in the cover, there is a risk of liquid pooling on the top surface of the second cover. Here, in this structure, the second cover and the motor structure are separate components, so it is difficult to apply the above-mentioned structure, in which liquid pooling on the top surface of the structure is drained through a drain hole provided in the structure.

The cover drainage structure that solves the above problem is a cover drainage structure that is assembled to the top of the engine structure. The cover is divided into a first cover having an opening and a second cover that is disposed below the opening. A through hole is formed in the second cover. The structure is formed with the through hole and a communication hole that is connected to the outside of the structure. A seal member is disposed between the through hole and the communication hole.

With this configuration, liquid that accumulates on the upper surface of the second cover is discharged through the through holes and communication holes that are sealed with a sealing member. This makes it possible to prevent liquid from accumulating in the recesses of the cover.

FIG. 2 is a perspective view of a cylinder head and an injector holder. FIG. 2 is a perspective view of a head cover and an injector. FIG. 4 is an end view of the head cover with the first tube and the second tube attached. FIG. 4 is an end view taken along line 4-4 shown in FIG.

An embodiment of the drainage structure of the cover will be described below.
The drainage structure in this embodiment is a structure applied to a head cover C attached to a cylinder head H of an internal combustion engine, which is a prime mover.

<Regarding the cylinder head of an internal combustion engine>
1, a cylinder head H of an internal combustion engine, which is a prime mover, includes a cylinder head body 10 fixed to a cylinder block (not shown), and a camshaft housing 20 fixed to the cylinder head body 10. In the following description, the cylinder block side of the cylinder head H is taken as the lower side, and the opposite side as the upper side.

The cylinder head body 10 has a generally rectangular parallelepiped shape and is made of a metal material such as an aluminum alloy. Four intake ports 11 are opened on one of a pair of side surfaces extending in the longitudinal direction of the cylinder head body 10. Each intake port 11 extends from the longitudinal side surface toward a combustion chamber defined on the underside of the cylinder head body 10. Outside air is supplied to the combustion chamber via these intake ports 11.

In addition, an exhaust port 12 for discharging exhaust gas from the combustion chamber is formed in the cylinder head body 10. The exhaust port 12 extends from the combustion chamber and opens on the side opposite to the side on which the intake port 11 opens.

Four first insertion holes 13 are defined on the intake port 11 side of the cylinder head body 10. The first insertion holes 13 are circular holes in a plan view, and penetrate the cylinder head body 10 from top to bottom. The four first insertion holes 13 are arranged at equal intervals in the longitudinal direction of the cylinder head body 10. The four first insertion holes 13 also extend parallel to one another.

Four second insertion holes 14 are defined on the exhaust port 12 side of the cylinder head body 10. Like the first insertion hole 13, the second insertion hole 14 is a circular hole in a plan view and penetrates the cylinder head body 10 in the vertical direction. The four second insertion holes 14 are arranged at equal intervals in the longitudinal direction of the cylinder head body 10. As shown in FIG. 3, the central axis J2 of the four second insertion holes 14 is not parallel to the central axis J1 of the first insertion hole 13 in a cross-sectional view including both the central axis J1 of the first insertion hole 13 and the central axis J2 of the second insertion hole 14. In other words, the central axis J2 of the second insertion hole 14 and the central axis J1 of the first insertion hole 13 extend in an approximately V-shape.

As shown in FIG. 1, the first tube 23 is attached to the first insertion hole 13. The first tube 23 is cylindrical, and the outer diameter of the first tube 23 is approximately the same as the inner diameter of the first insertion hole 13. The first tube 23 is inserted into the first insertion hole 13 so as to be coaxial with the first insertion hole 13. In other words, the central axis of the first tube 23 is the central axis J1 of the first insertion hole 13. The axial length of the first tube 23 is longer than the axial length of the first insertion hole 13, and a portion of the first tube 23 protrudes from the first insertion hole 13 toward the upper side of the cylinder head body 10.

A second tube 24 is attached to the second insertion hole 14. The second tube 24 is cylindrical, and the outer diameter of the second tube 24 is approximately the same as the inner diameter of the second insertion hole 14. The second tube 24 is inserted into the second insertion hole 14 so as to be coaxial with the second insertion hole 14. In other words, the central axis of the second tube 24 is the central axis J2 of the second insertion hole 14. The axial length of the second tube 24 is longer than the axial length of the second insertion hole 14, and a portion of the second tube 24 protrudes from the second insertion hole 14 toward the upper side of the cylinder head body 10.

As described above, the first insertion hole 13 and the second insertion hole 14 extend in a generally V-shape in cross section as shown in FIG. 3. Accordingly, the first tube 23 and the second tube 24 also extend non-parallel to form a generally V-shape in cross section including both the central axis J1 of the first insertion hole 13 and the central axis J2 of the second insertion hole 14.

As shown in FIG. 3, a rod-shaped injector 50 for injecting fuel into the combustion chamber is inserted into the first tube 23. The injector 50 is positioned and protected by the first tube 23. The tip of the injector 50 faces the combustion chamber, and a portion of the base end of the injector 50 is exposed above the first tube 23.

A roughly rod-shaped spark plug 60 is inserted into the second tube 24 to add fuel injected into the combustion chamber. The spark plug 60 is positioned and protected by the second tube 24. The tip of the spark plug 60 faces the combustion chamber, and a portion of the base end of the spark plug 60 is exposed above the second tube 24.

As shown in FIG. 1, a camshaft housing 20 made of a metal material such as an aluminum alloy is fixed to the upper surface of the cylinder head body 10 constructed as described above.
The camshaft housing 20 has an outer frame portion 21 in the shape of a rectangular frame. That is, the outer frame portion 21 is composed of a pair of long side walls 21a extending in the longitudinal direction of the outer frame portion 21 and a pair of short side walls 21b extending in the lateral direction of the outer frame portion 21 so as to connect the ends of the pair of long side walls 21a. Two camshaft insertion holes 22a are provided in one of the pair of short side walls 21b. Each camshaft insertion hole 22a penetrates the short side wall 21b in the longitudinal direction of the outer frame portion 21. The two camshaft insertion holes 22a are arranged on both sides of the center of the outer frame portion 21 in the lateral direction.

Four camshaft support parts 25 are provided inside the outer frame part 21. Each camshaft support part 25 extends in the short direction so as to connect a pair of long side walls 21a. In this embodiment, the camshaft support parts 25 are arranged at approximately equal intervals in the longitudinal direction of the outer frame part 21.

Each camshaft support portion 25 is provided with two camshaft insertion holes 22b. Each camshaft insertion hole 22b penetrates the camshaft support portion 25 in the longitudinal direction of the outer frame portion 21. The two camshaft insertion holes 22b are arranged on both sides of the center of the outer frame portion 21 in the lateral direction. In addition, the camshaft insertion holes 22b of the camshaft support portion 25 are arranged so as to be coaxial with the camshaft insertion holes 22a of the short side wall 21b described above.

When the camshaft housing 20 is attached to the top surface of the cylinder head body 10, the first tube 23 and the second tube 24 protrude slightly above the camshaft housing 20 through the space surrounded by the outer frame portion 21 and the camshaft support portion 25.

<About head covers>
A head cover C is attached to the camshaft housing 20 so as to cover the camshaft housing 20 from above.

As shown in FIG. 2, the head cover C has a split structure with a head cover body 34 as a first cover and an injector holder 33 as a second cover. Both the head cover body 34 and the injector holder 33 are made of a resin material.

The injector holder 33 has a generally rectangular shape overall, and has a plate-shaped flat portion 33A. The length of the injector holder 33 in the longitudinal direction is shorter than the length of the camshaft housing 20 in the longitudinal direction. On the other hand, the length of the injector holder 33 in the short side direction is shorter than the short side of the camshaft housing 20.

Four circular first mounting holes 43 penetrate the flat surface portion 33A. The four first mounting holes 43 are aligned in the longitudinal direction of the injector holder 33. The pitch between the central axes of the first mounting holes 43 matches the pitch between the central axes J1 of the first tubes 23. An annular seal material 40 is fitted into each of the first mounting holes 43.

The injector holder 33 is fixed to the cylinder head H via a number of bolts (not shown). As shown in FIG. 3, when the injector holder 33 is fixed to the cylinder head body 10, the upper end of the first tube 23 protruding from the camshaft housing 20 is fitted into the first mounting hole 43 via the seal material 40. Therefore, the injector holder 33 is attached to the upper surface of the camshaft housing 20 so as to cover the periphery of the portion where the first tube 23 protrudes.

As shown in FIG. 2, the head cover body 34 is generally in the shape of a rectangular plate. The longitudinal length of the head cover body 34 is approximately the same as the longitudinal length of the camshaft housing 20. The lateral length of the head cover body 34 is approximately the same as the lateral length of the camshaft housing 20. Therefore, the head cover body 34 serves as a cover that covers the entire camshaft housing 20.

Three openings 42 are formed in the head cover body 34. The three openings 42 are aligned in the longitudinal direction of the head cover body 34. Of the openings 42 aligned in the longitudinal direction, the openings 42 at both ends have an area larger than the openings of the first mounting holes 43. Of the openings 42 aligned in the longitudinal direction, the central opening 42 has an area that encompasses the openings of the two first mounting holes 43. The injector holder 33 is disposed below the three openings 42. When the head cover body 34 is viewed from above in a plan view with the injector holder 33 attached, the entire area of the first mounting hole 43 can be seen through the opening 42 of the head cover body 34.

Four circular second mounting holes 44 penetrate the head cover body 34. Each second mounting hole 44 is located on one side of the short side of the head cover body 34 with respect to the opening 42 described above. The four second mounting holes 44 are aligned in the longitudinal direction of the head cover body 34. The pitch between the central axes of the second mounting holes 44 is the same as the pitch between the central axes J2 of the second tubes 24. An annular seal material 41 is fitted into each second mounting hole 44. In FIG. 2, a portion of the seal material 41 is shown by a two-dot chain line.

The head cover body 34 is fixed to the cylinder head H via multiple bolts (not shown) while being positioned above the injector holder 33. Some of the bolts for fixing the head cover body 34 are also fixed to the injector holder 33. Although not shown, a gasket (not shown) is disposed between the injector holder 33 and the head cover body 34. This gasket fills the gap between the injector holder 33 and the head cover body 34, and the injector holder 33 and the head cover body 34 function as a single unit to form the head cover C.

As shown in FIG. 3, when the head cover body 34 is fixed to the cylinder head H, the upper end of the second tube 24 protruding from the camshaft housing 20 is fitted into the second mounting hole 44 via the sealing material 41.

When assembling the cylinder head of this embodiment, the camshaft housing 20 is attached to the cylinder head body 10 to form the cylinder head H, and then the injector holder 33 is attached to the top of the cylinder head H.

When attaching the injector holder 33 to the cylinder head H, the first mounting hole 43 of the injector holder 33 is fitted, via the seal material 40, to the upper end of the first tube 23 extending from the cylinder head body 10. When fitting the first mounting hole 43 to the first tube 23, the injector holder 33 is assembled while being moved toward the cylinder head H along the central axis direction of the first tube 23.

After the injector holder 33 is attached to the cylinder head H, the head cover body 34 is assembled to the injector holder 33 and the upper surface of the cylinder head H. At this time, the second mounting hole 44 of the head cover body 34 is fitted to the upper end of the second tube 24 extending from the cylinder head body 10 via the seal material 41. When fitting the second mounting hole 44 to the second tube 24, the head cover body 34 is assembled while moving it toward the cylinder head H along the central axis direction of the second tube 24. Then, a bolt is inserted into the head cover body 34 to fix it to the cylinder head H and the injector holder 33.

In this embodiment, the head cover C is divided into the injector holder 33 and the head cover main body 34. Therefore, when inserting the first tube 23 into the first mounting hole 43, the injector holder 33 can be moved in a direction along the central axis J1 of the first tube 23 for assembly. Also, when inserting the second tube 24 into the second mounting hole 44, the head cover main body 34 can be moved in a direction along the central axis J2 of the second tube 24 for assembly. Therefore, even if the direction of the central axis J1 of the first tube 23 and the direction of the central axis J2 of the second tube 24 are different, the head cover C can be easily attached without interfering with each tube.

<Drainage structure>
The head cover C has a divided structure into a head cover main body 34 having an opening 42, and an injector holder 33 disposed below the opening 42. Therefore, the injector holder 33 is a member that forms the bottom surface of the recess in the head cover C. More specifically, the flat surface portion 33A of the injector holder 33 forms the bottom surface of the recess in the head cover C. Therefore, there is a risk that a liquid pool containing various liquids will form on the upper surface of the injector holder 33, i.e., the upper surface of the flat surface portion 33A.

Therefore, this embodiment is provided with a discharge structure for discharging the liquid accumulated in the injector holder 33. The discharge structure will be described below.
1, 2, and 4, one through hole 70 is formed in the flat surface portion 33A of the injector holder 33. This through hole 70 is formed in a corner portion 33K of the flat surface portion 33A. This corner portion 33K is a portion located at the lowermost portion in the vertically downward direction on the flat surface portion 33A when the internal combustion engine to which the head cover C is attached is mounted on a vehicle. In addition, the through hole 70 is formed at a position that is lower in the vertically downward direction than the seal material 40 that is fitted into the first mounting hole 43 of the flat surface portion 33A.

As shown in Figs. 1 and 4, a protrusion 80 is formed on one of the pair of short side walls 21b of the camshaft housing 20, which is a structural member of the internal combustion engine, more specifically, on the short side wall 21ba where the camshaft insertion hole 22a is not provided. This protrusion 80 protrudes from the short side wall 21ba toward the inside of the camshaft housing 20. The protrusion 80 is formed on the intake port 11 side with respect to the center of the short side of the outer frame portion 21. The protrusion 80 has the through hole 70 and a communication hole 81 that connects to the outside of the camshaft housing 20 when the injector holder 33 is assembled to the camshaft housing 20.

As shown in FIG. 4, the communication hole 81 is a generally L-shaped hole, and one end side opens so as to connect to the through hole 70. The other end side of the communication hole 81 opens toward the outside of the short side wall 21ba. As a result, the other end side of the communication hole 81 opens to a wall surface other than the long side wall 21ae, which is located on the exhaust port 12 side of the pair of long side walls 21a.

A seal member 90 is disposed between the through hole 70 and the communication hole 81. This seal member 90 is annular and made of a material with a small Young's modulus, such as a rubber-based material.

<Action and Effects>
The operation and effects of this embodiment will be described.
(1) Liquid that accumulates on the upper surface of the injector holder 33, which forms the bottom surface of the recess in the head cover C, is discharged through the through hole 70 and the communication hole 81, which are sealed with the seal member 90. This makes it possible to prevent liquid from accumulating in the portion that forms the recess in the head cover C. This also makes it possible to prevent, for example, corrosion and deterioration of the injector holder 33.

(2) When the internal combustion engine with the head cover C attached is mounted on the vehicle, a through hole 70 is provided in the corner 33K located at the bottom in the vertically downward direction of the flat surface 33A. Therefore, liquid that accumulates on the upper surface of the injector holder 33 is directed toward the through hole 70 by the action of gravity. This improves the dischargeability of the liquid that accumulates on the upper surface of the injector holder 33.

(3) The through hole 70 is formed at a position that is lower in the vertical downward direction than the sealing material 40 that is fitted into the first mounting hole 43 of the flat surface portion 33A. Therefore, liquid present around the sealing material 40 is discharged to the outside through the through hole 70. This makes it possible to suppress corrosion and deterioration of the sealing material 40 due to liquid accumulation.

(4) The injector holder 33 and the camshaft housing 20 are made of different materials and have different thermal expansion coefficients. Therefore, depending on the temperature, the relative displacement between the through hole 70 and the communication hole 81 may increase, causing the holes to become misaligned. Even if the injector holder 33 and the camshaft housing 20 are made of the same material, if the temperatures of the injector holder 33 and the camshaft housing 20 are different, the relative displacement between the through hole 70 and the communication hole 81 may increase, causing the holes to become misaligned. In this regard, in this embodiment, a seal member 90 with a small Young's modulus and easy to deform is disposed between the through hole 70 and the communication hole 81. Therefore, even if the relative displacement between the through hole 70 and the communication hole 81 increases and causes the holes to become misaligned, the seal member 90 deforms in response to the relative displacement, thereby maintaining the sealability. Therefore, the reliability of the sealability provided by the seal member 90 is improved.

(5) An exhaust manifold, which becomes hot during engine operation or immediately after engine shutdown, is connected to the exhaust port 12. If liquid discharged from the other end of the communication hole 81 falls on such an exhaust manifold, the exhaust manifold may be rapidly cooled and, for example, damaged. In this regard, in this embodiment, the other end of the communication hole 81 opens toward the outside of the short side wall 21ba. In other words, it opens into a wall surface different from the long side wall 21ae located on the exhaust port 12 side. Therefore, damage to the exhaust manifold due to rapid cooling can be suppressed.

<Example of change>
This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

- Although a through hole 70 is provided in the corner 33K of the injector holder 33, the position of the through hole 70 can be changed as appropriate. If the position of the through hole 70 is changed, the position of the communication hole 81 is also changed accordingly.

The number of through holes 70 formed in the injector holder 33 may be changed as appropriate.
A groove extending toward through hole 70 may be formed on the surface of flat portion 33A. In this case, liquid that accumulates on the upper surface of injector holder 33 is smoothly guided to through hole 70 via the groove. This reduces the amount of liquid that accumulates on the upper surface of injector holder 33, thereby further suppressing, for example, corrosion and deterioration of injector holder 33.

- A material with a larger Young's modulus than rubber-based materials, such as a metal material or a resin material, may be used as the sealing member 90. Even in this case, effects other than those described above in (4) can be obtained.

The other end of the communication hole 81 may be open toward the outside of the long side wall 21ae. Even in this case, an effect other than the above-mentioned (5) can be obtained.
The second cover is the injector holder 33 having the first mounting hole 43 . However, the second cover may be a cover that does not have such a first mounting hole 43 .

The short side wall 21b is formed with the protrusion 80. Alternatively, the thickness of the short side wall 21b may be increased, and the communication hole 81 may be provided in the portion where the thickness is increased.
Although the communication hole 81 is a generally L-shaped hole, it may have another shape.

The cover with the split structure was the head cover C of an internal combustion engine. In addition, the prime mover may be an electric motor, and the drainage structure described above may be applied to a split cover that is attached to the top of the motor.

- In the above embodiment, the number of intake ports 11 and exhaust ports is four, i.e., an internal combustion engine with four cylinders is assumed, but the present invention may be applied to internal combustion engines with other numbers of cylinders. In other words, the numbers of the first tubes 23, second tubes 24, first insertion holes 13, second insertion holes 14, first mounting holes 43, and second mounting holes 44 may be adjusted to match the number of cylinders of the internal combustion engine.

The components attached to the first tube 23 and the second tube 24 are not limited to the combination of the injector 50 and the spark plug 60, but may be other combinations. For example, a spark plug may be attached to each tube, as in an internal combustion engine that employs a twin plug system.

- In the above embodiment, the first tube 23 and the second tube 24 were attached to the cylinder head body 10. However, the above-mentioned division structure may be applied to a head cover of an internal combustion engine in which a third tube or more tubes are arranged non-parallel to each other in addition to the first tube 23 and the second tube 24. In that case, a holder that plays a role similar to the injector holder 33 is added according to the increased number of tubes.

- In the above embodiment, when the head cover C is viewed from above, as long as the entire opening of the first mounting hole 43 of the injector holder 33 located at the bottom of the head cover body 34 can be confirmed from the opening 42 of the head cover body 34, the number and shape of the openings 42 may be changed as appropriate.

- In the above embodiment, the cylinder head H has a cylinder head body 10 and a camshaft housing 20 that supports the camshaft, which are separate members. Alternatively, the cylinder head may have a cylinder head body 10 and a camshaft housing 20 that are integrally formed.

- In the above embodiment, there is a cross section that includes both the central axis J1 of the first insertion hole 13 and the central axis J2 of the second insertion hole 14. However, the first insertion hole 13 and the second insertion hole 14 may be arranged so that the central axis J1 of the first insertion hole 13 and the central axis J2 of the second insertion hole 14 are not on the same plane. However, in any case, the central axes J1 of all the first insertion holes 13 are arranged parallel to each other, and the central axes J2 of all the second insertion holes 14 are arranged parallel to each other.

- In the above embodiment, the first tube 23 arranged on the intake port 11 side is attached to the first mounting hole 43 of the injector holder 33, and the second tube 24 arranged on the exhaust port 12 side is attached to the second mounting hole 44 of the head cover main body 34. On the other hand, the combination of the tubes arranged on the intake port 11 side and the exhaust port 12 side and the head cover is not limited. For example, the second tube 24 may be arranged on the intake port side and the second tube 24 may be attached to the second mounting hole 44 of the head cover main body 34.

- The assembly procedure for the cylinder head described in the above embodiment is an example, and the procedure may be modified as appropriate.

C...Head cover H...Cylinder head 10...Cylinder head body 11...Intake port 12...Exhaust port 13...First insertion hole 14...Second insertion hole 20...Camshaft housing 21ae...Long side wall 21ba...Short side wall 23...First tube 24...Second tube 33...Injector holder 33A...Flat portion 33K...Corner portion 34...Head cover body 40...Sealing material 41...Sealing material 42...Opening 43...First mounting hole 44...Second mounting hole 50...Injector 60...Spark plug 70...Through hole 80...Protrusion 81...Communicating hole 90...Sealing member

Claims (1)

A drainage structure for a cover that is attached to an upper portion of a cylinder head , comprising:
The cover is divided into a first cover having an opening and a second cover disposed below the opening,
The second cover has a through hole formed therein,
The cylinder head is formed with the through hole and a communication hole that is connected to the outside of the cylinder head ,
A seal member is disposed between the through hole and the communication hole,
the through hole and the communication hole are formed on the intake port side with respect to a center in a lateral direction of the cylinder head,
The communication hole is open to a wall surface of the side wall of the cylinder head opposite to the side wall located on the exhaust port side.
Drainage structure of the cover.

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