Positive crankcase ventilation (“PCV”) valve mounting structure

Abstract

A positive crankcase ventilation (PCV) valve mounting structure has a blow-by gas passage with an upstream-side passage portion and a down-stream-side passage portion positioned in a cylinder head and an intake manifold, respectively. The blow-by gas passage may receive the PCV valve therein such that an upstream side portion of a valve case of the PCV valve is positioned within the upstream-side passage portion and that a downstream side portion of the valve case is positioned within the down-stream-side passage portion when the cylinder head and the intake manifold are joined together. A gasket may seal the cylinder head to the intake manifold and may include a seal portion positioned between the valve case of the PCV valve and at least one of the cylinder head and the intake manifold.

Claims

1. A positive crankcase ventilation (PCV) valve mounting structure for mounting a PCV valve to an engine cylinder head and to an intake manifold, wherein the engine cylinder head contacts the intake manifold at a joint surface of the cylinder head and a joint surface of the intake manifold, the PCV valve mounting structure comprising: a blow-by gas passage with an upstream-side passage portion in the cylinder head and a down-stream-side passage portion in the intake manifold; wherein the upstream-side passage portion and the down-stream-side passage portion allow for fluid communication when the cylinder head and the intake manifold are joined together; wherein the blow-by gas passage is configured to receive the PCV valve therein such that an upstream side portion of a valve case of the PCV valve is positioned within the upstream-side passage portion and that a downstream side portion of the valve case of the PCV is positioned within the down-stream-side passage portion when the cylinder head and the intake manifold are joined together; wherein the PCV valve adjusts a flow of blow-by gas flowing through the blow-by gas passage; and a gasket positioned between the joint surface of the cylinder head and the joint surface of the intake manifold; wherein the gasket includes a seal portion positioned between the valve case of the PCV valve and one of the cylinder head and the intake manifold, the seal portion contacting the valve case and contacting one of the cylinder head and the intake manifold to form a seal between the valve case and one of the cylinder head and the intake manifold when the cylinder head and the intake manifold are joined together.

2. The PCV valve mounting structure of claim 1, further comprising: a seal ring that seals the valve case of the PCV valve to the other of the cylinder head and the intake manifold.

3. The PCV valve mounting structure of claim 1, wherein: a receiving-side stepped portion is formed at the joint surface of one of the cylinder head and the intake manifold; an insertion-side stepped portion is formed on the valve case of the PCV valve; and the seal portion of the gasket is interposed between the receiving-side stepped portion and the insertion-side stepped portion.

4. The PCV valve mounting structure of claim 1, wherein a seal member of the gasket is arranged to extend into the cylinder head and the intake manifold.

5. The PCV valve mounting structure of claim 1, wherein: the seal portion of the gasket is arranged to extend across the joint surface of the cylinder head and the joint surface of the intake manifold.

6. The PCV valve mounting structure of claim 1, wherein the PCV valve is arranged between two adjacent delivery passages formed in the intake manifold for distributing intake air.

7. The PCV valve mounting structure of claim 1, wherein the seal portion is formed integrally with the gasket.

8. The PCV valve mounting structure of claim 1, wherein the engine includes at least one intake air delivery passage extending across the joint surface of the cylinder head and the joint surface of the intake manifold; and wherein the gasket is configured to prevent leakage of intake air from the engine via the at least one intake air delivery passage.

9. A positive crankcase ventilation (PCV) valve mounting structure for mounting a PCV valve to an engine cylinder head and to an intake manifold, the engine cylinder head and the intake manifold being joined together at a joint surface of the cylinder head and a joint surface of the intake manifold, the PCV valve mounting structure comprising: a blow-by gas passage with an upstream-side passage portion in the cylinder head and a down-stream-side passage portion in the intake manifold; wherein the upstream-side passage portion and the down-stream-side passage portion allow for fluid communication upon joining the cylinder head to the intake manifold; wherein the blow-by gas passage is configured to receive the PCV valve therein such that an upstream side portion of a valve case of the PCV valve is positioned within the upstream-side passage portion and that a downstream side portion of the valve case is positioned within the down-stream-side passage portion when the cylinder head and the intake manifold are joined together; wherein the PCV valve is configured to adjust a flow of blow-by gas flowing through the blow-by gas passage; and a seal accommodation space in the blow-by gas passage between an outer circumferential surface of the valve case of the PCV valve and an inner circumferential wall of at least one of the upstream-side passage portion and the downstream-side passage portion; wherein at least a part of the seal accommodation space is positioned proximal to or across the joint surface of the cylinder head and the joint surface of the intake manifold, so that the at least a part of the seal accommodation space is open to at least one of the joint surfaces; and a first seal member disposed within the seal accommodation space such that the first seal member prevents leakage of the blow-by gas from the blow-by gas passage to an outside of the engine between the joint surface of the cylinder head and the joint surface of the intake manifold.

10. The PCV valve mounting structure of claim 9, wherein: the seal accommodation space is defined between a first stepped portion formed at the joint surface of one of the cylinder head and the intake manifold and a second stepped portion formed on the outer circumferential surface of the valve case of the PCV valve.

11. The PCV valve mounting structure of claim 9, wherein: the engine includes at least one intake air delivery passage extending across the joint surface of the cylinder head and the joint surface of the intake manifold; the first seal member is connected to a second seal member; the second seal member is positioned between the joint surface of the cylinder head and the joint surface of the intake manifold and configured to prevent leakage of air.

12. The PCV valve mounting structure of claim 11 wherein the second seal member is formed integrally with the first seal member.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a cross-sectional view of a side of a PCV valve mounting structure in accordance with a first embodiment;

(2) FIG. 2 is a schematic view illustrating a surface, such as a joining and/or contact surface, of a cylinder head of an intake manifold in accordance with the first embodiment;

(3) FIG. 3 is a cross-sectional view of a side of a PCV valve mounting structure in accordance with a second embodiment;

(4) FIG. 4 is a cross-sectional view of a side of a PCV valve mounting structure in accordance with a third embodiment;

(5) FIG. 5 a cross-sectional view of a side of a PCV valve mounting structure in accordance with a fourth embodiment; and

(6) FIG. 6 is a cross-sectional view of a side of a PCV valve mounting structure according to prior art.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

(7) A PCV valve mounting structure, in accordance with a first embodiment, will now be described with reference to FIGS. 1 and 2. Referring to FIG. 1, a blow-by gas passage 14 may have an upstream-side passage portion 15 positioned upstream from a down-stream side passage portion 16, with respect to a direction of flow of blow by gas through the blow-by gas passage 14. The upstream-side passage portion 15 may be formed in a cylinder head 10 of an engine. In detail, the downstream-side end of the upstream-side passage portion 15 may open at a joint surface 10a of the cylinder head 10. The upstream-side end of the upstream-side passage portion 15 may be in fluid communication with a gas mixing and/or transference chamber (not shown in FIGS.) into which the blow-by gas may flow from combustion chambers of the engine. The mixing chamber, as described here, may be a “crank” chamber located in, for example, a crankcase of the engine or may be a separation chamber of an oil separator coupled with the crank chamber. Also, the cylinder head 10 may be made of aluminum alloy and an engine (not shown in the FIGS.) having a cylinder block configured to accept the cylinder head 10 may be a multi-cylinder engine, such as a four-cylinder engine.

(8) The downstream-side passage portion 16 of the blow-by gas passage 14 may be formed in an intake manifold 12. The upstream-side end of the downstream-side passage portion 16 may open at a joint surface 12a of the intake manifold 12. The downstream-side end of the downstream-side passage portion 16 be in fluid communication with an intake air passage, such as one of distribution passages 20 (see FIG. 2) formed in the intake manifold 12 or an internal space of a serge tank (not shown). Further, the intake manifold 12 may be made of resin.

(9) The cylinder head 10 and the intake manifold 12 may be joined by a joining device (not shown in the FIGS.), such as a screw fastening device, a clipping device, and a snap-fitting device, such that the joint surface 10a of the cylinder head 12 and the joint surface 12a of the intake manifold contact with each other. In detail, the cylinder head 10 may be joined to and/or coupled with the intake manifold 12 such that all discussed interior passage portions (i.e. portions 15 and 16) are aligned (i.e. in series) across a common axis extending lengthwise, i.e. horizontally as shown in FIG. 1. A PCV valve 18 may be disposed in the blow-by gas passage 14 to extend between the passage portions 15 and 16.

(10) In an embodiment, the cylinder head 10 may be configured to define one or more of combustion chambers (not shown in the FIGS.), as well as intake and/or exhaust ports in correspondence with said chambers. Moreover, the intake manifold 12 may include a surge tank space (not shown in the FIGS.) and a plurality of delivery passages 20 (see FIG. 2). The delivery passages 20 may be connected to the downstream-side of the surge tank space and may distribute intake air (i.e. fresh air from outside the air intake and/or engine) to each intake port of the cylinder head 10.

(11) FIG. 2 schematically illustrates the joint surface 12a of the intake manifold 12, i.e. where the intake manifold 12 contacts the cylinder head 10. As shown here, the delivery passages 20 may open at the joint surface 12a. Further, the number of the delivery passages 20 may correspond to the number of engine cylinders (i.e., the number of the combustion chambers). In the embodiment shown here, four delivery passages 20 are provided, and their respective openings, are arranged in a row in the left-to-right direction as shown in FIG. 2. The downstream-side passage portion 16 of the gas passage 14 may open at a central position, i.e. in between two of the openings of the delivery passages 20. Moreover, a seal member or a gasket 22 shown in FIG. 2 may be positioned between the cylinder head 10 and the intake manifold 12 to form a seal therebetween.

(12) As shown in FIG. 1, the PCV valve 18 may have a valve case 24 that may generally enclose and/or define both a valve member 26 and a valve spring 28. Further, the valve case 24 may be made from a suitable rigid material, such as a metal having a desirable heat conductivity including stainless steel, aluminum alloy, iron and/or any composite formed thereof, and may be formed as a cylindrical tube, for example. The valve case 24, generally formed as a cylindrical tube as described here and/or as shown in at least FIG. 1, may extend lengthwise in the axial direction, i.e. the left-to-right direction in FIG. 1, to define a gas passage 34 through which gas may flow. In detail, the side (i.e. the right side as viewed in FIG. 1) corresponding to the upstream-side of the gas passage 34 of the valve case 24 will may be referred to as a “base end side.” Likewise, the side positioned opposite to the base end side, (i.e. left side as viewed in FIG. 1) corresponding to the downstream side of the gas passage 34, may be referred to as a “leading end side.”

(13) The inner circumferential surface of the valve case 24, also a wall and/or surface of the gas passage 34, may be formed with a gradient and/or stepped shape, such that the diameter of the inner circumferential surface of the valve case 24 gradually decreases from the base end side toward the leading end side. Moreover, the opening of the gas passage 34 on the leading end side may define a gas outlet 36. Similar to that described above for the inner circumferential surface of the valve case 24, the outer circumferential surface of the valve case 24 may also have a stepped shape, such that the valve case 24 has a first small diameter portion 38 positioned near and/or disposed on the base end side, a second small diameter portion 39 positioned near and/or disposed on the leading end side, and a large diameter portion 40 positioned near and/or disposed at an intermediate and/or center position between the first small diameter portion 38 and the second small diameter portion 39. In detail, the large diameter portion 40 may be positioned nearer to the leading end of the valve case 24. An insertion-side stepped portion 44 may be formed at a position where the outer circumferential surface of the second small diameter portion 39 intersects an end surface (i.e. a radially-surface) on the leading end side of the large diameter portion 40.

(14) An annular valve seat portion 45 (that may be shaped generally as a flange) may be formed on the inner circumferential surface of the gas passage 34 at a central position with respect to the axial direction of the gas passage 34. In detail, the annular valve seat portion 45 may be positioned closer to the leading end of the valve case 24 rather than the base end thereof. The valve seat portion 45 may be centered at and/or on an axis extending lengthwise, i.e. from left-to-right, across the cylinder head 10. The gas passage 34 may be centered around such an axis as described here and may have an inner diameter relatively smaller than that of the inner circumferential surface of the remaining portion of the gas passage 34. The inner diameter of the valve seat portion 45 may define a metering hole 46. A cushioning spring 52 may be disposed within the leading end side portion of the valve case 24. In detail, in an embodiment, the cushioning spring 52 may be a metal coil spring and thus be able to elastically inhibit excessive and/or otherwise undesirable movement of the valve member 26 toward the downstream side (i.e. the left side in FIG. 1). Further, the cushioning spring 52 may be inserted into the gas passage 34 via the base-end side opening of the valve case 24 until the cushioning spring 52 reaches an optimal and/or predetermined position, i.e. while still remaining within the leading end side portion of the valve case 24, after passing though the metering hole 46. Specifically, the cushioning spring 52 may be inserted into the gas passage 34 until touching and/or otherwise abutting a corresponding spring-receiving flange portion (not shown in FIG. 1) on an inner circumference of the gas outlet 36 at the base-end portion of the valve case 24.

(15) In an embodiment, the valve spring 28 may be a metal coil spring and may be inserted into the gas passage 34 until the valve spring 28 contacts and/or otherwise abuts to the valve seat 45. Thus, the valve seat 45 may function as a receiving portion for the valve spring 28. In detail, valve spring 38 may be compressed to move and/or bias the valve member 26 toward the upstream side (right side in FIG. 1) of the gas passage 34.

(16) The valve member 26 may be made of metal have a valve body portion 54 and a flange portion 56. The valve body portion 54 may be formed in a relatively rounded (i.e. cylindrical) rod shape. The flange portion 56 may protrude radially outward from the base end (i.e. the right end of the cylinder head 10 as shown in FIG. 1) of the valve body portion 54. In an embodiment, the outer circumferential surface of the flange portion 56 may be polygonal, i.e. having defined sides. In detail, the flange portion may be formed to have sides of equivalent length and/or at uniform angles to one another, i.e. to form a “regular” polygonal shape. The valve member 26 may be inserted into the base end side opening of the valve case 24 and may be move in the axial direction (left-to-right direction in FIG. 1) within the gas passage 34. In detail, the valve body portion 54 may be movably fitted into the valve spring 28 until the flange portion 56 contacts an end surface on the side of the base end of the valve spring 28. As described earlier, the polygonal outer circumferential surface of the flange portion 56 may slide and contact a side and/or wall surface of the gas passage 34, such that a plurality of flow openings (i.e. arranged in the circumferential direction) may be defined between the outer circumference of the flange portion 56 and the wall surface of the gas passage 34 for allowing passage of the blow-by gas.

(17) A metering surface 58 may be formed on the outer circumference of the leading end portion (i.e. toward downstream-side end portion as introduced and explained earlier) of the valve body portion 54. In detail, the metering surface 58 may be tapered in a direction toward the leading end of the valve body portion 54 such that the leading end portion of the valve body portion 54 may insert into the metering hole 46 of the valve seat 45, and a metering gap 60 may be defined between the inner circumferential surface of the metering hole 46 and the metering surface 58 of the valve body portion 26. The valve body portion 26 may draw away from and/or otherwise retract from the metering hole 46 (or move in a direction toward the upstream side) (right side in FIG. 1). As may be necessary to accommodate such movement of the valve body portion 26 as described here, an effective open area (i.e., the cross-sectional area) of the metering gap 60 may expand as needed. In comparison, as the valve body portion 26 advances into the metering hole 46 (or moves in a direction toward the downstream side), the passage cross-sectional area of the metering gap 60 may decrease, i.e. such that the cross-sectional area of the metering gap 60 becomes smaller.

(18) An annular removal-preventing member 62 may be fitted into the base-end side opening of the valve case 24 and may be fixed within the base end portion of the valve case 24 by a suitable fixation device and/or technique, such as by crimping. The inner circumference of the removal-preventing member 62 may define the gas inlet 64. Moreover, an O-ring 66 may be fitted into a corresponding O-ring receiving groove 42 formed in the outer circumferential surface of the valve case 24.

(19) Components associated with mounting the PCV valve 18 into the cylinder head 10 will now be described in further detail. As shown in FIG. 1, a stepped recess 70 may be formed at the joint surface 10a of the cylinder head 10 such that the open end of the upstream-side passage portion 15 is enlarged, i.e. “coaxially” enlarged about an axis extending lengthwise across the cylinder head 10. The stepped recess 70 may be sized to accommodate and/or fit with the large diameter portion 40 of the valve case 24. Further, a receiving-side stepped recess 72 may be formed at the joint surface 12a of the intake manifold 12 such that the open end of the downstream-side passage portion 16 is coaxially enlarged. Further, in an embodiment, the inner diameter of the stepped recess 70 may equal to or substantially equal to the inner diameter of the stepped recess 72.

(20) Referring now to that shown by FIG. 2, the gasket 22 may have a plurality of first seal portions 74, a plurality of connection portions 76 and a second seal portion 78. Each of the first seal portions 74 may be generally formed in the shape of rectangle and surround corresponding delivery passages 20. As described earlier, the number of the delivery passages 20 may correspond to the number of the engine cylinders. Thus, the number of the seal portions 74 may also correspond to the number of the engine cylinders. Each of the connection portions 76 may connect two adjacent seal portions 74. In further detail, one of the connection portions 76 connecting two adjacent seal portions 74 generally located at the center of the intake manifold 12 (i.e. in the orientation shown in FIG. 2) of the seal portions 74 may have the second seal portion 78. In detail, the second seal portion 78 may have an annular shape to elastically fit with the insertion-side stepped portion 44 of the valve case 24 and with the receiving-side stepped portion 72 of the intake manifold 12 (see FIG. 1). The gasket 22 may be inserted into a corresponding gasket fitting recess 80 formed at the joint surface 12a. Similarly, the second seal portion 78 may be fitted with the receiving-side stepped portion 72 at the same time the gasket 22 is fitted into the gasket fitting recess 80. In an embodiment, the receiving-side stepped portion 72 may be defined by a part of the gasket fitting recess 80. The second seal portion 78 may serve as a seal member and/or otherwise assist in sealing the PCV valve 18.

(21) Prior to joining the cylinder head 10 and the intake manifold 12 together as shown in FIG. 1 (i.e. such that the cylinder head 10 is pressed against the intake manifold 12), the gasket 22 may be fitted into the gasket fitting recess 80 formed at the joint surface 12a, such that the seal portion 78 may be fitted with the receiving-side stepped portion 72 as described above. Next, the large diameter portion 40 of the valve case 24 may be fitted into the stepped recess portion 70, and at the same time, the smaller diameter portion 38 on the base-end side of the valve case 24 may be fitted into the upstream-side passage portion 15 that may be in fluid communication with the stepped recess portion 70. Resultantly, the gas inlet 64 of the valve case 24 may be aligned with the upstream-side passage portion 15 to allow for gas to pass as needed. Following, the cylinder head 10 and the intake manifold 12 may be jointed together, such that the small diameter portion 39 on the leading-end side of the valve case 24 may be fitted into the downstream-side passage portion 16 after passing through the second seal portion 78 of the gasket 22. Thus, the gas outlet 36 of the valve case 24 may be aligned with the downstream-side passage portion 16 to allow gas to pass through the gas outlet 36 into the downstream-side passage portion 16 as needed. As a result, the PCV valve 18 may be inserted into and/or mounted within the cylinder head 10 and the intake manifold 12 to extend between the upstream-side passage portion 15 of the cylinder head 10 and the down-stream side passage portion 16 of the intake manifold 12.

(22) In the “mounted state” shown in FIG. 1 (i.e. in that the PCV 18 has been inserted into and/or retained within the cylinder head 10 as described above), the gasket 22 (see FIG. 2) may seal the joint surface 10a of the cylinder head 10 and the joint surface 12a of the intake manifold 12 to prevent possible leakage of intake air in, for example, the upstream-side passage portion 15. In addition, the second seal portion 78 of the gasket 22 may be positioned in between the insertion-side stepped portion 44 and the receiving-side stepped portion 72 of the intake manifold 12 to form a seal therebetween. Further, the O-ring 66 may be positioned between the valve case 24 and the inner circumferential surface of the stepped recess 70 of the cylinder head 10 to form a seal therebetween. Furthermore, the end surface on the base-end side of the large diameter portion 40 may press against and/or contact the bottom surface on the base-end side of the stepped recess 70 of the cylinder head 10.

(23) Upon starting the engine, a negative pressure produced in an intake passage (not shown in the drawings) of the intake manifold 12 may inside of a communication passage (not shown in the drawings) formed in the engine to facilitate the flow of the blow-by as may be needed for routine engine operation. Next, the blow-by gas may flow into passages 15 and 16. Also, in an embodiment, fresh air (i.e. atmospheric air) suctioned into the intake manifold 12 may be redirected into a fresh air introduction passage (not shown in the FIGS.). During redirection and/or re-circulation of the blow-by gas throughout the various passages, i.e. passages 15 and 16 and/or the fresh air introduction passage as described here, the PCV valve 18 may operate according to load applied to the engine and/or the negative pressure (relative to ambient air) produced in the intake passage, such that the quantity of the redirected and/or re-circulated blow-by gas flowing from the upstream-side passage 15 to the downstream-side passage 16 of the blow-by gas passage 14 may be controlled.

(24) In detail, the valve member 26 of the PCV valve 18 may move to a position where force, such as a returning and/or biasing force, of the valve spring 26 applied to the valve member 26 may be adjusted to compensate for and/or counterbalance to the intake negative pressure or pressure variances in, for example, the passages 15 and 16. Should a sudden reversal of gas flow direction occur, due to, for example a “misfire” and/or “backfire,” defined as irregular fuel combustion in the combustion chambers of the engine, the valve member 26 may move toward the removal-preventing member 62 of the valve case 24 such that the flange portion 56 of the valve member 26 may be seated on the removal-preventing member 62 to close the gas inlet 64. Accordingly, the blow-by gas passage 14 and the PCV valve 18 may be considered to constitute significant components of a blow-by gas recirculation system.

(25) With the PCV valve mounting structure described above, the second seal portion 78 that may also be a part of the gasket 22, may form a seal between the intake manifold 12 and the valve case 24 of the PCV valve 24. Therefore, the number of components necessary for the PCV valve mounting structure may be minimized. Accordingly, the costs associated with manufacturing the gas recirculation system may be controlled.

(26) Further, the O-ring 66 may form a seal between the cylinder head 10 and the valve case 24 of the PCV valve 18 to reliably prevent against unwanted leakage of blow-by gas from the passages 15 and 16 within the cylinder head 10.

(27) Moreover, the second seal portion 78 of the gasket 22 may be positioned between the receiving-side stepped portion 72 formed at the joint surface 12a of the intake manifold 12 and the insertion-side stepped portion 44 formed on the valve case 24. Thus, the seal portion 78 may be assembled relatively easily as needed to seal the intake manifold 12 to the valve case 24.

(28) In addition, the downstream-side passage portion 16 of the intake manifold 12 may be positioned between two adjacent delivery passages 20 (see FIG. 2). The delivery passages 20 may be in fluid communication with the intake ports (not shown in the FIGS.) of the cylinder head 10. Alternatively described, the PCV valve 18 may be positioned between two adjacent intake ports. This arrangement may increase the quantity of heat able to be transmitted from the cylinder head 10 to the PCV valve 18. This may inhibit unwanted adhesion and/or fixation of the valve member 26 that may be caused due to ice forming on and/or between the various components described here when the engine may be started in relatively cold temperatures.

(29) A second embodiment will now be described with reference to FIG. 3. The second embodiment is a modification of the first embodiment and thus shares many parts, components fixtures and/or the like with the first embodiment. Thus, like components are labeled with like reference numerals as the first embodiment, and a redundant description of the same will be omitted. The second embodiment differs from the first embodiment in that the second seal portion 78 of the gasket 22 extends into the open end of the stepped recess 70 of the cylinder head 10. Alternatively put, the second seal portion 78 extends across a joint plane where the joint surface 10a of the cylinder head 10 and the joint surface 12a of the intake manifold 12 are joined together. Thus, the second seal portion 78 may form a seal between the intake manifold 12 and the valve case 24 of the PCV valve 24 and may also form a seal between the cylinder head 10 and the valve case 24 of the PCV valve 24. For at least this reason, in particular as related to this (i.e. the second) embodiment, the O-ring 66 may be omitted.

(30) A third embodiment will now be described with reference to FIG. 4. As discussed above for the second embodiment, this (i.e. third) embodiment is a modification of the first embodiment and thus shares many parts, components, fixtures and/or the like with the first embodiment. Therefore, like components are labeled with like reference numerals as the first embodiment, and a redundant description of the same will be omitted. As shown in FIG. 4, this (third) embodiment differs from the first embodiment primarily in that (i) the O-ring 66 may be replaced with O-ring 88 and in that (ii) the arrangement position of the second seal portion 78 of the gasket 22 is changed. In this connection as shown by FIG. 4, the small diameter portion 39 on the leading-end side of the valve case 24 may include an annular groove 84 for accepting and/or fitting with the O-ring 88. The annular groove 84 may be toward the center of the cylinder head 10 (relative to the axial direction) of the outer circumferential surface of the small diameter portion 39. In addition, an insertion-side stepped portion 86 may be formed at a position where the outer circumferential surface of the small diameter portion 38 on the base-end side of the valve case 24 intersects the base end surface (i.e. the internal radial surface) of the large diameter portion 40.

(31) Also, a stepped recess 90 may be formed at the joint surface 12a of the intake manifold 12 such that the open end of the downstream-side passage portion 16 may be enlarged in the radial direction, i.e. coaxially enlarged. The stepped recess 90 may be sized to fit with the large diameter portion 40 of the valve case 24. Likewise, receiving-side stepped portion 92 may be formed at the joint surface 10a of the cylinder head 10 such that the open end of the upstream-side passage portion 15 is coaxially enlarged. In this embodiment, the receiving-side stepped portion 92 may be axially opposed to the insertion-side stepped portion 86. The inner diameter of the receiving-side stepped portion 92 may be equal to or substantially equal to the inner diameter of the stepped recess 90.

(32) Moreover, the gasket 22 may be fitted into the gasket fitting recess 80 formed at the joint surface 12a of the intake manifold 12, similar to that shown and discussed in connection with the first embodiment. However, in the third embodiment, the gasket 22 may be fitted into a gasket fitting recess (not shown in the FIGS.) formed at the joint surface 10a of the cylinder head 10 and configured to have a shape similar to that of the gasket fitting recess 80. Thus, each of the seal portions 74 may surround the open end of the corresponding intake port of the cylinder head 10, i.e. similar to that shown by FIG. 2.

(33) With this (i.e. third) embodiment, prior to joining the cylinder head 10 and the intake manifold 12 together, the gasket 22 may be fitted into the gasket fitting recess formed at the joint surface 10a of the cylinder head 10. At the same time, the second seal portion 78 of the gasket 22 may be fitted into the receiving-side stepped portion 92 of the cylinder head 10. Alternatively, the large diameter portion 40 of the valve case 24 may be fitted into the stepped recess portion 90 of the intake manifold 12, and at the same time, the small diameter portion 39 on the leading end side of the valve case 24 may be fitted into the downstream-side passage portion 16 on the downstream side of the stepped recess portion 90. Thus, the gas outlet 36 of the valve case 24 may be aligned with the downstream-side passage portion 16. Thereafter, the cylinder head 10 and the intake manifold 12 may be joined together, such that the small diameter portion 38 on the base-end side of the valve case 24 may be fitted into the upstream-side passage portion 15 after passing through the second seal portion 78 of the gasket 22. Thus, the gas inlet 64 of the valve case 24 may be aligned with the upstream-side passage portion 15 to allow for the PCV valve 18 to be mounted within the cylinder head 10 and the intake manifold 12. In detail, the PCV valve 18 may extend between the upstream-side passage portion 15 of the cylinder head 10 and the down-stream side passage portion 16 of the intake manifold 12.

(34) While the PCV 18 is mounted within the cylinder head 10 and the intake manifold 12 as shown in FIG. 4, similar to the first embodiment, the gasket 22 (see FIG. 2) may form a seal between the joint surface 10a of the cylinder head 10 and the joint surface 12a of the intake manifold 12. In addition, the second seal portion 78 of the gasket 22 may be positioned between the insertion-side stepped portion 86 of the valve case 24 and the receiving-side stepped portion 92 of cylinder head 10 so as to form a seal therebetween. Further, the end surface on the leading-end side of the large diameter portion 40 may abut and/or otherwise contact or slightly spaced from the bottom surface on the base-end side of the stepped recess 90 of the intake manifold 12.

(35) The PCV valve mounting structure of this (i.e. third) embodiment, similar to the first embodiment, provides the second seal portion 78, that is a part of the gasket 22, to form seal between the intake manifold 12 and the valve case 24 of the PCV valve 24. Therefore, the number of components necessary for the mounting structure may be minimized to thus reduce costs associated with manufacturing of the gas recirculation system.

(36) Further, the O-ring 88 may seal the intake manifold 12 to the valve case 24 of the PCV valve 18 to prevent potential leakage of the blow-by gas.

(37) Moreover, the second seal portion 78 of the gasket 22 may be positioned between the receiving-side stepped portion 92 formed at the joint surface 10a of the cylinder head 10 and the insertion-side stepped portion 86 formed on the valve case 24. Thus, the second seal portion 78 may be easily assembled for sealing between the cylinder head 10 and the valve case 24.

(38) A fourth embodiment will now be described with reference to FIG. 5. This embodiment is a modification of the third embodiment. Therefore, like components are labeled with like reference numerals as the third embodiment, and a redundant description of the same will be omitted. The fourth embodiment is different from the third embodiment in that the second seal portion 78 of the gasket 22 extends into the open end of the stepped recess 90 of the intake manifold 12. Alternatively described, the second seal portion 78 extends across a joint plane between the cylinder head 10 and the intake manifold 12. Thus, the second seal portion 78 may seal the cylinder head 10 to the valve case 24 of the PCV valve 24 and may also seal the intake manifold 12 to the valve case 24. For at least this reason, in particular as shown for this (fourth) embodiment, the O-ring 88 may be omitted.

(39) The above-described embodiments may be modified further in various ways. For example, the embodiments have been described for the PCV valve mounting structure for mounting one PCV valve to one blow-by gas passage connected to the engine. However, for example, if a plurality of blow-by gas passages are arranged in parallel with each other are also connected to the engine, a plurality of PCV valve mounting structures may be incorporated and/or configured with the blow-by gas passages as desired.

(40) In an embodiment, the valve case 24 may be made of resin instead of metal. Further, at least one of the valve portion 26, the valve spring 28 and the cushion spring 52 may be made of resin.

(41) Although the blow-by gas passage 14 into which the PCV valve 18 may be mounted is located at a position between the delivery passages 20 or between the intake ports, the blow-by gas passage 14 may be located, for example, on the outer peripheral side of the joint surfaces.

(42) Further, the cross-sectional shape of the seal portion 78 of the gasket 22 may not be limited to a circular shape but may be a rectangular shape or any other shape. Also, the number of the first seal portions 74 of the gasket 22 may not be limited to four but may be one, two, three or five or more to correspond to the number of the delivery passages 20. Even further, the O-rings 66 and 68 may be replaced with seal rings having a rectangular cross sectional shape or any other cross sectional shape.

(43) The various examples described above in detail with reference to the attached drawings are intended to be representative and thus not limiting. The detailed description is intended to teach a person of skill in the art to make, use and/or practice various aspects of the present teachings and thus is not intended to limit the scope of the invention. Furthermore, each of the additional features and teachings disclosed above may be applied and/or used separately or with other features and teachings to provide improved PCV valve mounting structures, and/or methods of making and using the same.

(44) Moreover, the various combinations of features and steps disclosed in the above detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught to describe representative examples. Further, various features of the above-described representative examples, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.

(45) All features disclosed in the description and/or the claims are intended to be disclosed as informational, instructive and/or representative and may thus be construed separately and independently from each other. In addition, all value ranges and/or indications of groups of entities are also intended to include possible intermediate values and/or intermediate entities for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter.