Patent Application
20090235892
The present invention relates to a cylinder head cover attached to an upper portion of a cylinder head of an engine and, more particularly, to a cylinder head cover incorporating an oil control valve for controlling hydraulic oil.
Conventionally, as one such type of cylinder head cover, a configuration disclosed in, for example, Japanese Laid-Open Patent Publication No. 2006-17085 has been proposed.
The outer shell portion 31a formed of synthetic resin and the valve casing 32 formed of metal have different heat expansion coefficients. Accordingly, if, for example, the temperature in the engine compartment rises, a gap may form in a boundary portion 35 between the outer shell portion 31a and the valve casing 32, leading to leakage of oil.
To solve the problem, the following configurations, for example, have been proposed conventionally.
(1) With adhesive applied to the outer circumferential surface of the valve casing 32, the outer shell portion 31a of the cylinder head cover 31 is molded onto the outer circumference of the valve casing 32. This bonds and fixes the outer shell portion 31a and the valve casing 32 to each other at the boundary portion 35.
(2) With reference to
(3) Also referring to
(4) As illustrated in
However, in the method using the adhesive as described in the item (1), when the synthetic resin is caused to fill a mold with the valve casing 32 set in the mold to form the outer shell portion 31a, the pressure of the synthetic resin, which is to be molded, is likely to urge the adhesive to flow out of the outer circumferential surface of the valve casing 32. This may make it impossible to effectively bond the outer shell portion 31a and the valve casing 32 together with the adhesive. Further, if the flowed out adhesive remains on the outer end surface of the valve casing 32, the appearance is degraded. Also, if the adhesive remains in the outer shell portion 31a as impurity, the oil may leak from the corresponding portion of the outer shell portion 31a.
If the method using the groove 36 as described in the above item (2) is employed, the outer shell portion 31a and the valve casing 32 can be fixed by the anchor effect so that the outer shell portion 31a and the valve casing 32 are not displaced with respect to each other. However, the formation of a gap between the valve casing 32 and the outer shell portion 31a cannot be prevented. Thus, the oil is likely to leak from the boundary portion 35.
In the method employing the seal ring 37 as described in the above items (3) and (4), when the synthetic resin is caused to fill the mold in which the valve casing 32 is set in order to form the outer shell portion 31a, the filling pressure of the synthetic resin must be set to an appropriate value. Otherwise, the seal ring 37 may not be allowed to seal the boundary portion 35. Specifically, if the filling pressure is insufficient, the seal ring 37 cannot be compressed to an appropriate extent and repulsive force necessary for sealing cannot be ensured. In contrast, if the filling pressure is excessively high, a great amount of synthetic resin may go over a parting line of the mold and causes a burr in a product. This complicates the post-molding process since the burr must be removed.
The present invention was made for solving the above problems in the prior art. It is an objective of the invention to provide a cylinder head cover that prevents oil from leaking to the exterior from a boundary portion between an outer shell portion formed of synthetic resin and a valve casing formed of metal.
To achieve the foregoing objective and in accordance with one aspect of the present invention, a cylinder head cover including an outer shell portion, a tubular valve casing, a valve body, an annular projection, and a seal ring is provided. The outer shell portion is formed of a synthetic resin. The tubular valve casing is formed of a metal and molded with the outer shell portion. The valve body is inserted into the valve casing through an opening formed at an end of the valve casing and incorporated in the valve casing. The annular projection is formed in the outer shell portion and projects toward the opening of the valve casing in such a manner as to cover a boundary portion between the outer shell portion and the valve casing. The seal ring is arranged between the projection and the valve body.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.
The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:
A first embodiment of the present invention will now be described with reference to
An opening 12a is formed in an outer end (the left end as viewed in
A valve body 16 of an oil control valve is inserted from the opening 12a of the valve casing 12 and incorporated in the valve casing 12. A seal ring 17 is attached to a portion of the outer circumference of the valve body 16 corresponding to the opening 12a of the valve casing 12. The seal ring 17 is located between the inner circumferential surface of the entering portion 15a of the projection 15 and the outer circumferential surface of the valve body 16. A plurality of oil grooves 18 having oil holes 18a are formed in the outer circumferential surface of the valve body 16. The inner end (the right end as viewed in
In the cylinder head cover 11 constructed as described above, the sealing performance between the valve casing 12 and the valve body 16 is maintained through the engagement between the entering portion 15a and the seal ring 17. As a result, even if a gap forms between the valve casing 12 and the outer shell portion 11a, the gap is prevented from communicating with the exterior.
The first embodiment has the following advantages.
(1) The annular projection 15, which is provided in the outer shell portion 11a, covers the boundary portion 19 between the inner circumferential surface of the outer shell portion 11a and the outer circumferential surface of the valve casing 12. Further, the seal ring 17, which is attached to the outer circumference of the valve body 16, seals the boundary portion between the inner circumferential surface of the projection 15 and the outer circumferential surface of the valve body 16. This configuration prevents oil from leaking to the exterior from the boundary portion 19 between the outer shell portion 11a formed of synthetic resin and the valve casing 12 formed of metal.
(2) The entering portion 15a extending from the inner edge of the projection 15 is inserted into the recess 14, which is formed in the inner surface of the end of the valve casing 12. The end of the valve casing 12 in the vicinity of the opening 12a is clamped by the entering portion 15a and the outer shell portion 11a. This suppresses deformation of the projection 15 in a manner separating from the end surface of the opening 12a of the valve casing 12 due to the difference between the thermal expansion rate of the outer shell portion 11a formed of synthetic resin and the thermal expansion rate of the valve casing 12 formed of metal. This, in turn, suppresses movement of the outer shell portion 11a caused by such deformation. Formation of a gap between the outer shell portion 11a and the valve casing 12 is thus prevented and, as a result, leakage of the oil to the exterior is effectively prevented.
(3) As has been described, since leakage of the oil to the exterior is prevented, it is unnecessary to apply adhesive between the outer shell portion 11a and the valve casing 12. As a result, degradation of the appearance caused by the adhesive that has been urged to flow out is prevented.
A second embodiment of the present invention will hereafter be explained mainly about the differences from the first embodiment.
As illustrated in
Accordingly, in the second embodiment, the advantages substantially equivalent to those of the first embodiment are obtained. Since the second embodiment is configured without the entering portion 15a, a gap may form easily between the outer shell portion 11a and the valve casing 12, compared to the first embodiment. However, even without the entering portion 15a, the engagement between the seal ring 17 and the projection 15 of the outer shell portion 11a prevents leakage of oil to the exterior.
A third embodiment of the present invention will now be described mainly about the differences from the first embodiment.
As illustrated in
An arcuate surface 21 is formed on the inner edge of the opening 12a of the valve casing 12, specifically, in a portion adjacent to the entering portion 15a at the inner edge of the opening 12a. An arcuate surface 23 is formed on the inner edge of the outer opening (the left side as viewed in
Accordingly, the third embodiment has the following advantages in addition to the advantages substantially equivalent to those of the first embodiment.
(4) The step 50, by which the inner circumferential surface 24 of the entering portion 15a retreats radially outward, is formed in the boundary portion between the entering portion 15a and the valve casing 12. Accordingly, if burr is formed in a portion of the outer shell portion 11a adjacent to the valve casing 12 when the outer shell portion 11a is molded, the step 50 prevents the burr from projecting toward the inner circumferential surface 22 of the valve casing 12. As a result, when the valve body 16 is inserted into and incorporated in the valve casing 12, the burr is prevented from being caught between the valve body 16 and the valve casing 12 or being cut off and falling in the cylinder head cover 11.
(5) The arcuate surface 23 and the arcuate surface 21 are formed in the entering portion 15a and the valve casing 12, respectively. As a result, when the valve body 16 is inserted into and incorporated in the valve casing 12, damage to the seal ring 17 is suppressed while such incorporation is smoothly accomplished.
A fourth embodiment of the present invention will hereafter be explained mainly about the differences from the third embodiment.
In the fourth embodiment, as illustrated in
The fourth embodiment has the following advantage in addition to the advantages substantially equivalent to those of the third embodiment.
(6) When the seal ring 17 arranged on the valve body 16 and the inner circumferential surface 24 are engaged with each other, force is generated on the inner circumferential surface 24 and presses the seal ring 17 toward the inner side of the entering portion 15a. This prevents the seal ring 17 from deforming outward (to the left side as viewed in
A fifth embodiment of the present invention will now be described mainly about the differences from the first embodiment.
With reference to
The fifth embodiment has the following advantages in addition to the advantages substantially equivalent to those of the first embodiment.
(7) The seal ring 17 having the multiple lip portions 17a enhances the sealing performance between the projection 15 and the valve body 16 without increasing the surface pressure of the seal ring 17 acting on the projection 15.
(8) Even if the surface pressure of the seal ring 17, or the force acting on the projection 15 of the outer shell portion 11a in a radially outward direction, is small, the sealing performance of the seal ring 17 is ensured. This suppresses deformation of the outer shell portion 11a in a direction separating from the valve casing 12. Formation of a gap between the outer shell portion 11a and the valve casing 12 is thus prevented.
The illustrated embodiments may be modified as follows.
In the configuration with the entering portion 15a formed at the inner edge of the projection 15 as in the first embodiment, the lip seal 17 having the multiple lip portions 17a may be employed as in the fifth embodiment.
In the configuration without the entering portion 15a as in the second embodiment, a step may be formed between the inner circumferential surface of the projection 15 and the inner circumferential surface of the valve casing 12 as in the third embodiment. Further, as in the fourth embodiment, arcuate portions may be formed at the inner edge of the valve casing 12 or the inner edge of the projection 15.
The inner circumferential surface 24 of the entering portion 15a may be inclined in the direction opposite to that of the third embodiment. In other words, the inner circumferential surface 24 may be inclined in such a manner that the inner circumferential surface 24 retreats further along a direction toward the outer side of the valve casing 12.
An annular groove may be formed in the inner circumferential surface of the projection 15 or the entering portion 15a, and a seal ring engaged with the outer circumferential surface of the valve body 16 may be fitted in the annular groove.
Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-069945 | Mar 2008 | JP | national |
