Positive crankcase ventilation (“PCV”) valve mounting structure

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.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims priority to Japanese Patent Application Serial No. 2014-224163 filed on Nov. 4, 2014, the contents of which are incorporated herein by reference in their entirety for all purposes.

Not applicable.

BACKGROUND

The invention generally relates to a structure for mounting a positive crankcase ventilation valve (herein referred to as a “PCV” valve) to a cylinder head of an internal combustion engine, such as an engine for powering an automobile and/or any other vehicle engine. Further, the PCV valve may be mounted directly to an intake manifold of such an engine. Also, the PCV valve may direct and/or adjust flow of gas that may be recirculated from the engine and/or exhaust system of a vehicle, for example, back to the engine to enhance engine power delivery and efficiency.

FIG. 6illustrates a known PCV valve mounting structure. As shown inFIG. 6, a blow-by gas passage106includes an upstream-side passage portion108and a downstream-side passage portion112formed in a cylinder head102and an intake manifold104of the engine, respectively. The upstream-side passage portion108and the downstream-side passage portion112of the blow-by gas passage106may communicate with each other when the cylinder head102and the intake manifold104come into contact. A PCV valve100is mounted within the upstream-side passage portion108and the downstream-side passage portion112to extend therebetween. In detail, the PCV valve100may adjust flow rate of blow-by gas flowing though the blow-by passage106. A stepped recess portion110, with a diameter larger than the downstream-side passage portion112, is formed in the cylinder head102at an open end portion of the upstream-side passage portion108.

The PCV valve100has a valve case114, a valve member116positioned within and extending internally throughout the valve case114and a valve spring118. The valve case114includes a main case portion114aand a sub-case portion114b, both main and sub case portions114aand114bbeing made of resin. The main case portion114aand the sub-case portion114bare joined to each other in the axial direction (i.e., the left-to-right direction inFIG. 6) to collectively define a gas passage120. A valve seat122made of metal is held between a right side end portion of the main case portion114aand a left side end portion of the sub-case portion114bto be coaxial with both the main and sub-case portions114aand114b. The valve seat122has an annular plate shape with a metering hole122aformed therein. The valve member116enters into the gas passage120, so that a cross-sectional passage area (i.e. the open area) of the metering hole122aof the valve seat122may be adjusted in response to the axial movement of the valve member116. The valve spring118biases the valve member116in an upstream-side direction (i.e. toward the left inFIG. 6) with respect to the gas passage120. The downstream-side end of the PCV valve100(i.e., the right-side end of the sub-case portion114binFIG. 6) is fitted into the open-ended portion of the downstream-side passage portion112of the intake manifold104. The remaining portion of the sub-case portion114bis fitted into the stepped recess portion110of the cylinder head102, and the main case portion114ais also fitted into the stepped portion110. A metering space124is defined as the region between the inner circumferential surface of the metering hole122aof the valve seat122and the outer circumferential surface (i.e. metering surface) of the valve member116.

A first O-ring126seals the cylinder head102to the valve case114and may fit into a corresponding first O-ring groove (not shown inFIG. 6) in the main case portion114a. Similarly, a second O-ring128seals the intake manifold104to the valve case114and may fit into corresponding second O-ring groove (not shown inFIG. 6) formed in the sub-case portion114b. A gasket130is positioned between joint surfaces of the cylinder head102and the intake manifold104and is fitted into a corresponding gasket-receiving groove in the joint surface of the intake manifold104.

U.S. Patent Application Publication No. US2011/0203559 (also published as Japanese Laid-Open Patent Publication No. 2011-169258) generally discloses a PCV mounting structure similar to that shown inFIG. 6.

In detail, the mounting structure shown inFIG. 6involves two O-rings, i.e., the first O-ring126for sealing the cylinder head102to the valve case114, and the second O-ring128for sealing the intake manifold104to the valve case114as described above. Such an arrangement may result in difficulty in mounting the O-ring126and the O-ring128to the main case portion114aand the sub-case portion114b, respectively. Further, the operations for forming the O-ring grooves in the main and sub-case portions114aand114bare relatively involved and/or time-consuming. Thus, such an arrangement as described above may lead to an increase in costs associated with manufacturing and/or maintaining, for example, the mounting structure.

In view of the challenges discussed above, there is a need in the art for a PCV valve mounting structure with fewer components needed for operation, thus also contributing to a commensurate reduction in production costs associated with such a PCV valve mounting structure.

SUMMARY

A PCV valve mounting structure in accordance with an embodiment includes a PCV valve (positive crankcase ventilation valve) mounted to an engine cylinder head and to an intake manifold. The cylinder head may contact the intake manifold at a defined surface. The PCV valve mounting structure has a gas passage, i.e. a passage able to accommodate “blow-by” gas, with an upstream-side passage portion in the cylinder head and a corresponding down-stream-side passage portion in the intake manifold. The upstream and the down-stream-side passage portions may be in fluid communication when the cylinder head contacts and/or joins the intake manifold. The blow-by gas passage receives the PCV valve therein such that an upstream side portion of a valve case of the PCV valve is inside the upstream-side passage portion of the cylinder head. Further, the PCV valve may be inserted into the gas passage, as described here, such that a downstream side portion of the valve case of the PCV valve is within the down-stream-side passage portion of the cylinder head when the cylinder head and the intake manifold join together. Moreover, once inserted into the gas passage, the PCV valve may adjust flow of blow-by gas flowing through the blow-by gas passage. In an embodiment, the PCV valve has a valve member movable longitudinally, i.e. along the length-wise direction of the PCV valve and/or gas passage, in response to a pressure variance between the upstream and downstream sides of the PCV valve that may occur while the PCV valve adjusts the cross-sectional area of the gas passage, i.e. as may be generally defined by a valve seat of the valve case. A gasket may be positioned on and/or at a surface where the cylinder head meets the intake manifold to prevent unwanted leakage of intake air through an intake air passage(s) formed in the engine. The gasket may have a seal portion positioned between the valve case of the PCV valve and either the cylinder head and the intake manifold to form a seal therebetween when the cylinder head contacts and/or joins the intake manifold.

In such an arrangement as described above, the gasket may seal the cylinder head to the intake manifold and, in an embodiment, the gasket may also seal the valve case of the PCV valve to either the cylinder head or the intake manifold. By allowing for the selection of the particular component to which the gasket forms a seal and/or seals, the overall number of components of the mounting structure may be minimized to accordingly reduce and/or control costs associated with manufacturing the mounting structure.

The PCV valve mounting structure may further include a seal ring that seals the valve case of the PCV valve to either of the cylinder head and the intake manifold.

In an embodiment, a receiving-side stepped portion may be formed on and/or at one of the joint surfaces of the cylinder head and the intake manifold. Similarly, an insertion-side stepped portion may be formed on the valve case of the PCV valve. In such an arrangement as described here, a seal portion of the gasket may be positioned between the receiving-side stepped portion and the insertion-side stepped portion to allow for relatively easy assembly and/or positioning of the seal portion between the valve case of the PCV valve and the cylinder head or the intake manifold.

In an embodiment, a seal member of the gasket may extend into both of the cylinder head and the intake manifold to allow for the simultaneous seal between the valve case of the PCV valve and the cylinder head, as well as between the valve case and the intake manifold.

The PCV valve may be positioned between two adjacent intake air delivery passages in the intake manifold. In detail, the blow-by gas passage may be formed in the engine between two adjacent delivery passages in the intake manifold or between two adjacent intake ports in the cylinder head in communication with the two adjacent delivery passages. With this arrangement, heat generated by operation the engine may be transmitted to the PCV valve as needed to thus prevent “icing” and/or “fixation,” i.e. defined where a valve is fixed in a given position, of a valve member of the PCV valve against the wall of the gas passage when the engine is started in cold weather conditions.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

A PCV valve mounting structure, in accordance with a first embodiment, will now be described with reference toFIGS. 1 and 2. Referring toFIG. 1, a blow-by gas passage14may have an upstream-side passage portion15positioned upstream from a down-stream side passage portion16, with respect to a direction of flow of blow by gas through the blow-by gas passage14. The upstream-side passage portion15may be formed in a cylinder head10of an engine. In detail, the downstream-side end of the upstream-side passage portion15may open at a joint surface10aof the cylinder head10. The upstream-side end of the upstream-side passage portion15may 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 head10may be made of aluminum alloy and an engine (not shown in the FIGS.) having a cylinder block configured to accept the cylinder head10may be a multi-cylinder engine, such as a four-cylinder engine.

The downstream-side passage portion16of the blow-by gas passage14may be formed in an intake manifold12. The upstream-side end of the downstream-side passage portion16may open at a joint surface12aof the intake manifold12. The downstream-side end of the downstream-side passage portion16be in fluid communication with an intake air passage, such as one of distribution passages20(seeFIG. 2) formed in the intake manifold12or an internal space of a serge tank (not shown). Further, the intake manifold12may be made of resin.

The cylinder head10and the intake manifold12may 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 surface10aof the cylinder head12and the joint surface12aof the intake manifold contact with each other. In detail, the cylinder head10may be joined to and/or coupled with the intake manifold12such that all discussed interior passage portions (i.e. portions15and16) are aligned (i.e. in series) across a common axis extending lengthwise, i.e. horizontally as shown inFIG. 1. A PCV valve18may be disposed in the blow-by gas passage14to extend between the passage portions15and16.

In an embodiment, the cylinder head10may 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 manifold12may include a surge tank space (not shown in the FIGS.) and a plurality of delivery passages20(seeFIG. 2). The delivery passages20may 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 head10.

FIG. 2schematically illustrates the joint surface12aof the intake manifold12, i.e. where the intake manifold12contacts the cylinder head10. As shown here, the delivery passages20may open at the joint surface12a. Further, the number of the delivery passages20may correspond to the number of engine cylinders (i.e., the number of the combustion chambers). In the embodiment shown here, four delivery passages20are provided, and their respective openings, are arranged in a row in the left-to-right direction as shown inFIG. 2. The downstream-side passage portion16of the gas passage14may open at a central position, i.e. in between two of the openings of the delivery passages20. Moreover, a seal member or a gasket22shown inFIG. 2may be positioned between the cylinder head10and the intake manifold12to form a seal therebetween.

As shown inFIG. 1, the PCV valve18may have a valve case24that may generally enclose and/or define both a valve member26and a valve spring28. Further, the valve case24may 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 case24, generally formed as a cylindrical tube as described here and/or as shown in at leastFIG. 1, may extend lengthwise in the axial direction, i.e. the left-to-right direction inFIG. 1, to define a gas passage34through which gas may flow. In detail, the side (i.e. the right side as viewed inFIG. 1) corresponding to the upstream-side of the gas passage34of the valve case24will 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 inFIG. 1) corresponding to the downstream side of the gas passage34, may be referred to as a “leading end side.”

The inner circumferential surface of the valve case24, also a wall and/or surface of the gas passage34, may be formed with a gradient and/or stepped shape, such that the diameter of the inner circumferential surface of the valve case24gradually decreases from the base end side toward the leading end side. Moreover, the opening of the gas passage34on the leading end side may define a gas outlet36. Similar to that described above for the inner circumferential surface of the valve case24, the outer circumferential surface of the valve case24may also have a stepped shape, such that the valve case24has a first small diameter portion38positioned near and/or disposed on the base end side, a second small diameter portion39positioned near and/or disposed on the leading end side, and a large diameter portion40positioned near and/or disposed at an intermediate and/or center position between the first small diameter portion38and the second small diameter portion39. In detail, the large diameter portion40may be positioned nearer to the leading end of the valve case24. An insertion-side stepped portion44may be formed at a position where the outer circumferential surface of the second small diameter portion39intersects an end surface (i.e. a radially-surface) on the leading end side of the large diameter portion40.

An annular valve seat portion45(that may be shaped generally as a flange) may be formed on the inner circumferential surface of the gas passage34at a central position with respect to the axial direction of the gas passage34. In detail, the annular valve seat portion45may be positioned closer to the leading end of the valve case24rather than the base end thereof. The valve seat portion45may be centered at and/or on an axis extending lengthwise, i.e. from left-to-right, across the cylinder head10. The gas passage34may 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 passage34. The inner diameter of the valve seat portion45may define a metering hole46. A cushioning spring52may be disposed within the leading end side portion of the valve case24. In detail, in an embodiment, the cushioning spring52may be a metal coil spring and thus be able to elastically inhibit excessive and/or otherwise undesirable movement of the valve member26toward the downstream side (i.e. the left side inFIG. 1). Further, the cushioning spring52may be inserted into the gas passage34via the base-end side opening of the valve case24until the cushioning spring52reaches an optimal and/or predetermined position, i.e. while still remaining within the leading end side portion of the valve case24, after passing though the metering hole46. Specifically, the cushioning spring52may be inserted into the gas passage34until touching and/or otherwise abutting a corresponding spring-receiving flange portion (not shown inFIG. 1) on an inner circumference of the gas outlet36at the base-end portion of the valve case24.

In an embodiment, the valve spring28may be a metal coil spring and may be inserted into the gas passage34until the valve spring28contacts and/or otherwise abuts to the valve seat45. Thus, the valve seat45may function as a receiving portion for the valve spring28. In detail, valve spring38may be compressed to move and/or bias the valve member26toward the upstream side (right side inFIG. 1) of the gas passage34.

The valve member26may be made of metal have a valve body portion54and a flange portion56. The valve body portion54may be formed in a relatively rounded (i.e. cylindrical) rod shape. The flange portion56may protrude radially outward from the base end (i.e. the right end of the cylinder head10as shown inFIG. 1) of the valve body portion54. In an embodiment, the outer circumferential surface of the flange portion56may 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 member26may be inserted into the base end side opening of the valve case24and may be move in the axial direction (left-to-right direction inFIG. 1) within the gas passage34. In detail, the valve body portion54may be movably fitted into the valve spring28until the flange portion56contacts an end surface on the side of the base end of the valve spring28. As described earlier, the polygonal outer circumferential surface of the flange portion56may slide and contact a side and/or wall surface of the gas passage34, such that a plurality of flow openings (i.e. arranged in the circumferential direction) may be defined between the outer circumference of the flange portion56and the wall surface of the gas passage34for allowing passage of the blow-by gas.

A metering surface58may 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 portion54. In detail, the metering surface58may be tapered in a direction toward the leading end of the valve body portion54such that the leading end portion of the valve body portion54may insert into the metering hole46of the valve seat45, and a metering gap60may be defined between the inner circumferential surface of the metering hole46and the metering surface58of the valve body portion26. The valve body portion26may draw away from and/or otherwise retract from the metering hole46(or move in a direction toward the upstream side) (right side inFIG. 1). As may be necessary to accommodate such movement of the valve body portion26as described here, an effective open area (i.e., the cross-sectional area) of the metering gap60may expand as needed. In comparison, as the valve body portion26advances into the metering hole46(or moves in a direction toward the downstream side), the passage cross-sectional area of the metering gap60may decrease, i.e. such that the cross-sectional area of the metering gap60becomes smaller.

An annular removal-preventing member62may be fitted into the base-end side opening of the valve case24and may be fixed within the base end portion of the valve case24by a suitable fixation device and/or technique, such as by crimping. The inner circumference of the removal-preventing member62may define the gas inlet64. Moreover, an O-ring66may be fitted into a corresponding O-ring receiving groove42formed in the outer circumferential surface of the valve case24.

Components associated with mounting the PCV valve18into the cylinder head10will now be described in further detail. As shown inFIG. 1, a stepped recess70may be formed at the joint surface10aof the cylinder head10such that the open end of the upstream-side passage portion15is enlarged, i.e. “coaxially” enlarged about an axis extending lengthwise across the cylinder head10. The stepped recess70may be sized to accommodate and/or fit with the large diameter portion40of the valve case24. Further, a receiving-side stepped recess72may be formed at the joint surface12aof the intake manifold12such that the open end of the downstream-side passage portion16is coaxially enlarged. Further, in an embodiment, the inner diameter of the stepped recess70may equal to or substantially equal to the inner diameter of the stepped recess72.

Referring now to that shown byFIG. 2, the gasket22may have a plurality of first seal portions74, a plurality of connection portions76and a second seal portion78. Each of the first seal portions74may be generally formed in the shape of rectangle and surround corresponding delivery passages20. As described earlier, the number of the delivery passages20may correspond to the number of the engine cylinders. Thus, the number of the seal portions74may also correspond to the number of the engine cylinders. Each of the connection portions76may connect two adjacent seal portions74. In further detail, one of the connection portions76connecting two adjacent seal portions74generally located at the center of the intake manifold12(i.e. in the orientation shown inFIG. 2) of the seal portions74may have the second seal portion78. In detail, the second seal portion78may have an annular shape to elastically fit with the insertion-side stepped portion44of the valve case24and with the receiving-side stepped portion72of the intake manifold12(seeFIG. 1). The gasket22may be inserted into a corresponding gasket fitting recess80formed at the joint surface12a. Similarly, the second seal portion78may be fitted with the receiving-side stepped portion72at the same time the gasket22is fitted into the gasket fitting recess80. In an embodiment, the receiving-side stepped portion72may be defined by a part of the gasket fitting recess80. The second seal portion78may serve as a seal member and/or otherwise assist in sealing the PCV valve18.

Prior to joining the cylinder head10and the intake manifold12together as shown inFIG. 1(i.e. such that the cylinder head10is pressed against the intake manifold12), the gasket22may be fitted into the gasket fitting recess80formed at the joint surface12a, such that the seal portion78may be fitted with the receiving-side stepped portion72as described above. Next, the large diameter portion40of the valve case24may be fitted into the stepped recess portion70, and at the same time, the smaller diameter portion38on the base-end side of the valve case24may be fitted into the upstream-side passage portion15that may be in fluid communication with the stepped recess portion70. Resultantly, the gas inlet64of the valve case24may be aligned with the upstream-side passage portion15to allow for gas to pass as needed. Following, the cylinder head10and the intake manifold12may be jointed together, such that the small diameter portion39on the leading-end side of the valve case24may be fitted into the downstream-side passage portion16after passing through the second seal portion78of the gasket22. Thus, the gas outlet36of the valve case24may be aligned with the downstream-side passage portion16to allow gas to pass through the gas outlet36into the downstream-side passage portion16as needed. As a result, the PCV valve18may be inserted into and/or mounted within the cylinder head10and the intake manifold12to extend between the upstream-side passage portion15of the cylinder head10and the down-stream side passage portion16of the intake manifold12.

In the “mounted state” shown inFIG. 1(i.e. in that the PCV18has been inserted into and/or retained within the cylinder head10as described above), the gasket22(seeFIG. 2) may seal the joint surface10aof the cylinder head10and the joint surface12aof the intake manifold12to prevent possible leakage of intake air in, for example, the upstream-side passage portion15. In addition, the second seal portion78of the gasket22may be positioned in between the insertion-side stepped portion44and the receiving-side stepped portion72of the intake manifold12to form a seal therebetween. Further, the O-ring66may be positioned between the valve case24and the inner circumferential surface of the stepped recess70of the cylinder head10to form a seal therebetween. Furthermore, the end surface on the base-end side of the large diameter portion40may press against and/or contact the bottom surface on the base-end side of the stepped recess70of the cylinder head10.

Upon starting the engine, a negative pressure produced in an intake passage (not shown in the drawings) of the intake manifold12may 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 passages15and16. Also, in an embodiment, fresh air (i.e. atmospheric air) suctioned into the intake manifold12may 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. passages15and16and/or the fresh air introduction passage as described here, the PCV valve18may 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 passage15to the downstream-side passage16of the blow-by gas passage14may be controlled.

In detail, the valve member26of the PCV valve18may move to a position where force, such as a returning and/or biasing force, of the valve spring26applied to the valve member26may be adjusted to compensate for and/or counterbalance to the intake negative pressure or pressure variances in, for example, the passages15and16. 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 member26may move toward the removal-preventing member62of the valve case24such that the flange portion56of the valve member26may be seated on the removal-preventing member62to close the gas inlet64. Accordingly, the blow-by gas passage14and the PCV valve18may be considered to constitute significant components of a blow-by gas recirculation system.

With the PCV valve mounting structure described above, the second seal portion78that may also be a part of the gasket22, may form a seal between the intake manifold12and the valve case24of the PCV valve24. 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.

Further, the O-ring66may form a seal between the cylinder head10and the valve case24of the PCV valve18to reliably prevent against unwanted leakage of blow-by gas from the passages15and16within the cylinder head10.

Moreover, the second seal portion78of the gasket22may be positioned between the receiving-side stepped portion72formed at the joint surface12aof the intake manifold12and the insertion-side stepped portion44formed on the valve case24. Thus, the seal portion78may be assembled relatively easily as needed to seal the intake manifold12to the valve case24.

In addition, the downstream-side passage portion16of the intake manifold12may be positioned between two adjacent delivery passages20(seeFIG. 2). The delivery passages20may be in fluid communication with the intake ports (not shown in the FIGS.) of the cylinder head10. Alternatively described, the PCV valve18may be positioned between two adjacent intake ports. This arrangement may increase the quantity of heat able to be transmitted from the cylinder head10to the PCV valve18. This may inhibit unwanted adhesion and/or fixation of the valve member26that 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.

A second embodiment will now be described with reference toFIG. 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 portion78of the gasket22extends into the open end of the stepped recess70of the cylinder head10. Alternatively put, the second seal portion78extends across a joint plane where the joint surface10aof the cylinder head10and the joint surface12aof the intake manifold12are joined together. Thus, the second seal portion78may form a seal between the intake manifold12and the valve case24of the PCV valve24and may also form a seal between the cylinder head10and the valve case24of the PCV valve24. For at least this reason, in particular as related to this (i.e. the second) embodiment, the O-ring66may be omitted.

A third embodiment will now be described with reference toFIG. 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 inFIG. 4, this (third) embodiment differs from the first embodiment primarily in that (i) the O-ring66may be replaced with O-ring88and in that (ii) the arrangement position of the second seal portion78of the gasket22is changed. In this connection as shown byFIG. 4, the small diameter portion39on the leading-end side of the valve case24may include an annular groove84for accepting and/or fitting with the O-ring88. The annular groove84may be toward the center of the cylinder head10(relative to the axial direction) of the outer circumferential surface of the small diameter portion39. In addition, an insertion-side stepped portion86may be formed at a position where the outer circumferential surface of the small diameter portion38on the base-end side of the valve case24intersects the base end surface (i.e. the internal radial surface) of the large diameter portion40.

Also, a stepped recess90may be formed at the joint surface12aof the intake manifold12such that the open end of the downstream-side passage portion16may be enlarged in the radial direction, i.e. coaxially enlarged. The stepped recess90may be sized to fit with the large diameter portion40of the valve case24. Likewise, receiving-side stepped portion92may be formed at the joint surface10aof the cylinder head10such that the open end of the upstream-side passage portion15is coaxially enlarged. In this embodiment, the receiving-side stepped portion92may be axially opposed to the insertion-side stepped portion86. The inner diameter of the receiving-side stepped portion92may be equal to or substantially equal to the inner diameter of the stepped recess90.

Moreover, the gasket22may be fitted into the gasket fitting recess80formed at the joint surface12aof the intake manifold12, similar to that shown and discussed in connection with the first embodiment. However, in the third embodiment, the gasket22may be fitted into a gasket fitting recess (not shown in the FIGS.) formed at the joint surface10aof the cylinder head10and configured to have a shape similar to that of the gasket fitting recess80. Thus, each of the seal portions74may surround the open end of the corresponding intake port of the cylinder head10, i.e. similar to that shown byFIG. 2.

With this (i.e. third) embodiment, prior to joining the cylinder head10and the intake manifold12together, the gasket22may be fitted into the gasket fitting recess formed at the joint surface10aof the cylinder head10. At the same time, the second seal portion78of the gasket22may be fitted into the receiving-side stepped portion92of the cylinder head10. Alternatively, the large diameter portion40of the valve case24may be fitted into the stepped recess portion90of the intake manifold12, and at the same time, the small diameter portion39on the leading end side of the valve case24may be fitted into the downstream-side passage portion16on the downstream side of the stepped recess portion90. Thus, the gas outlet36of the valve case24may be aligned with the downstream-side passage portion16. Thereafter, the cylinder head10and the intake manifold12may be joined together, such that the small diameter portion38on the base-end side of the valve case24may be fitted into the upstream-side passage portion15after passing through the second seal portion78of the gasket22. Thus, the gas inlet64of the valve case24may be aligned with the upstream-side passage portion15to allow for the PCV valve18to be mounted within the cylinder head10and the intake manifold12. In detail, the PCV valve18may extend between the upstream-side passage portion15of the cylinder head10and the down-stream side passage portion16of the intake manifold12.

While the PCV18is mounted within the cylinder head10and the intake manifold12as shown inFIG. 4, similar to the first embodiment, the gasket22(seeFIG. 2) may form a seal between the joint surface10aof the cylinder head10and the joint surface12aof the intake manifold12. In addition, the second seal portion78of the gasket22may be positioned between the insertion-side stepped portion86of the valve case24and the receiving-side stepped portion92of cylinder head10so as to form a seal therebetween. Further, the end surface on the leading-end side of the large diameter portion40may abut and/or otherwise contact or slightly spaced from the bottom surface on the base-end side of the stepped recess90of the intake manifold12.

The PCV valve mounting structure of this (i.e. third) embodiment, similar to the first embodiment, provides the second seal portion78, that is a part of the gasket22, to form seal between the intake manifold12and the valve case24of the PCV valve24. 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.

Further, the O-ring88may seal the intake manifold12to the valve case24of the PCV valve18to prevent potential leakage of the blow-by gas.

Moreover, the second seal portion78of the gasket22may be positioned between the receiving-side stepped portion92formed at the joint surface10aof the cylinder head10and the insertion-side stepped portion86formed on the valve case24. Thus, the second seal portion78may be easily assembled for sealing between the cylinder head10and the valve case24.

A fourth embodiment will now be described with reference toFIG. 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 portion78of the gasket22extends into the open end of the stepped recess90of the intake manifold12. Alternatively described, the second seal portion78extends across a joint plane between the cylinder head10and the intake manifold12. Thus, the second seal portion78may seal the cylinder head10to the valve case24of the PCV valve24and may also seal the intake manifold12to the valve case24. For at least this reason, in particular as shown for this (fourth) embodiment, the O-ring88may be omitted.

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.

In an embodiment, the valve case24may be made of resin instead of metal. Further, at least one of the valve portion26, the valve spring28and the cushion spring52may be made of resin.

Although the blow-by gas passage14into which the PCV valve18may be mounted is located at a position between the delivery passages20or between the intake ports, the blow-by gas passage14may be located, for example, on the outer peripheral side of the joint surfaces.

Further, the cross-sectional shape of the seal portion78of the gasket22may not be limited to a circular shape but may be a rectangular shape or any other shape. Also, the number of the first seal portions74of the gasket22may not be limited to four but may be one, two, three or five or more to correspond to the number of the delivery passages20. Even further, the O-rings66and68may be replaced with seal rings having a rectangular cross sectional shape or any other cross sectional shape.

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.

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.