Cylinder head gasket

A cylinder head gasket 1 has a gas seal plate P1 in which a combustion chamber hole 11 is drilled, an oil seal plate P2 in which an oil hole 13 is drilled, and a main plate P3 provided between the gas seal plate and the oil seal plate. Plate thicknesses of the gas seal plate, the oil seal plate, and the main plate are made different from each other, the plate thickness of the gas seal plate is larger than the plate thicknesses of the oil seal plate and the main plate, and end portions of the gas seal plate, the oil seal plate, and the main plate are connected to each other. A combustion gas, lubricant oil or the like from a combustion chamber or an oil passage can be effectively sealed, and the cylinder head gasket can be manufactured inexpensively.

TECHNICAL FIELD

The present invention relates to a cylinder head gasket, and more particularly to a cylinder head gasket sandwiched between a cylinder block and a cylinder head in which a combustion chamber, an oil passage, a water passage, and a bolt insertion passage are formed and provided with a combustion chamber hole drilled at a position of the combustion chamber and an oil hole drilled at a position of the oil passage.

BACKGROUND ART

A cylinder head gasket sandwiched between a cylinder block and a cylinder head in which a combustion chamber, an oil passage, a water passage, and a bolt insertion passage are formed and provided with a combustion chamber hole drilled at a position of the combustion chamber and an oil hole drilled at a position of the oil passage has conventionally been known.

In such cylinder gaskets, a load is concentrated at a periphery of the combustion chamber in order to seal a combustion gas from the combustion chamber hole, and specifically, those with an increased plate thickness at the periphery of the combustion chamber hole or with beads surrounding the combustion chamber hole formed are known (Patent Documents 1 to 7).

PRIOR ART DOCUMENTS

Patent Literature

SUMMARY OF INVENTION

Problems to be Solved by the Invention

However, as a result of the concentration of the load to the periphery of the combustion chamber hole, leakage of lubricant oil and the like from the oil passage formed in the cylinder block and the cylinder head causes a problem, and an improvement of the sealing properties in the portion has been in demand.

In view of such a problem, the present invention provides an inexpensive cylinder head gasket capable of effectively sealing a combustion gas or the lubricant oil from the combustion chamber and the oil passage.

Means for Solving the Problems

That is, a cylinder head gasket according to the present invention is a cylinder head gasket sandwiched between a cylinder block and a cylinder head in which a combustion chamber, an oil passage, a water passage, and a bolt insertion passage are formed and provided with a combustion chamber hole drilled at a position of the combustion chamber and an oil hole drilled at a position of the oil passage, whereinthe cylinder head gasket comprises a gas seal plate in which the combustion chamber hole is drilled, an oil seal plate in which the oil hole is drilled, and a main plate provided between the gas seal plate and oil seal plate;the plate thicknesses of the gas seal plate, the oil seal plate, and the main plate are made different from each other, and the plate thickness of the gas seal plate is set larger than the plate thicknesses of the oil seal plate and the main plate; andend portions of the gas seal plate, the oil seal plate, and the main plate are connected to each other.

Advantageous Effects of the Invention

According to the above-described invention, since the plate thicknesses of the gas seal plate, the oil seal plate, and the main plate are made different from each other, and the plate thickness of the gas seal plate is set larger than the plate thicknesses of the oil seal plate and the main plate, a load to the gas seal plate can be concentrated during assembling of an engine, and a combustion gas can be effectively sealed.

Moreover, since the plate thicknesses of the oil seal plate and the main plate are made different from each other, loads acting on the oil seal plate and the main plate can be made different and the load in the periphery of the oil hole can be adjusted, whereby lubricant oil can be sealed.

Moreover, since the combustion gas, the lubricant oil and the like can be effectively sealed, even in a single-layer cylinder head gasket in which three plates are connected, a cylinder head gasket can be obtained inexpensively.

MODE FOR CARRYING OUT THE INVENTION

The present invention will be described below by referring to illustrated embodiments.FIG. 1illustrates a plan view of a cylinder head gasket1according to a first embodiment, and as illustrated inFIGS. 2 and 3, the cylinder head gasket1is sandwiched between a cylinder head2and a cylinder block3.

Four combustion chambers aligned on a straight line, a bolt insertion passage which connects the cylinder head2and the cylinder block3to each other, and an oil passage through which lubricant oil and a blowby gas communicate are provided in the cylinder head2and the cylinder block3.

Moreover, a water passage through which cooling water communicates is formed in the cylinder block3and the cylinder head2, and this water passage is formed of a water jacket4a(a two-dot-chain line in theFIG. 2) formed on the cylinder block3and surrounding the combustion chamber and a head-side water passage4b(seeFIG. 3) formed in the cylinder head2and formed so as to overlap at least a part of the water jacket4a.

In the cylinder head gasket1, a combustion chamber hole11drilled at a position of the combustion chamber, a bolt hole12drilled at a position of the bolt insertion passage, an oil hole13drilled at a position of the oil passage, and a water hole14through which the water jacket4aand the head-side water passage4bconstituting the water passage communicate with each other are provided.

Then, the cylinder head gasket1of this embodiment has a configuration in which three types of plates P1to P3with different plate thicknesses are connected and comprises the gas seal plate P1in which the combustion chamber hole11is drilled, the oil seal plate P2in which the oil hole13is drilled, and the main plate P3provided between the gas seal plate P1and the oil seal plate P2and in which the bolt hole12and the water hole14are drilled.

The plate thickness of the gas seal plate P1is larger than the plate thicknesses of the oil seal plate P2and the main plate P3as illustrated inFIG. 2, and the plate thickness of the oil seal plate P2is smaller than that of the main plate P3as illustrated inFIG. 2.

Moreover, end portions of the gas seal plate P1, the oil seal plate P2, and the main plate P3are abutted to each other so as not to overlap, and the abutment portions are connected by spot welding, laser welding or the like.

Furthermore, coatings are formed on front surfaces and back surfaces of the gas seal plate P1, the oil seal plate P2, and the main plate P3, and the plate thicknesses of the gas seal plate P1, the oil seal plate P2, and the main plate P3include the thickness of the formed coatings.

The coating is made of a material such as fluorine, nitrile rubber or the like or an elastomer and is provided for the purpose of the improvement of close contact and sealing properties with the opposite material, but a top coating such as graphite or wax may be applied on a surface of the coating in order to ensure slip properties or non-adhesiveness as necessary.

As illustrated inFIG. 2, the plate thickness reference of the cylinder head gasket1is on the cylinder block3side in this embodiment, but this plate thickness reference may be on the cylinder head2side or on a plate thickness center of each of the plates P1to P3.

An outer edge of the gas seal plate P1is located outside of an inner edge portion of an opening portion of the water jacket4a, and an inner edge of the main plate P3is connected at the substantially center of the water jacket4a.

As described above, by connecting the gas seal plate P1and the main plate P3within a range of the opening portion of the water jacket4a, the concentration of a stress to a connection position where the plate thicknesses are different is prevented during engine assembling.

The connection position between the gas seal plate P1and the main plate P3may be located closer to the combustion chamber hole11side than the inner edge of the opening portion of the water jacket4ain order to increase a contact pressure at the periphery of the combustion chamber.

Subsequently, a full bead15surrounding each of the four combustion chamber holes11and swollen toward the cylinder head2is provided on the gas seal plate P1.

A one-dot-chain line inFIG. 1indicates a position of a ridge line on a top in each of the above-described full beads15or each of half beads described below.

This full bead15, as an inner bead, is formed inwardly of the opening portion of the water jacket4aand when sandwiched between the cylinder block3and the cylinder head2, the combustion gas from the combustion chamber hole11is sealed by this full bead15and also cooling water from the above-described water passage is sealed.

The oil seal plate P2is provided on each of the four oil passages formed in the cylinder block3and the cylinder head2and its outer edge is formed so that a width from the opening portion of the oil hole13becomes as small as possible.

Moreover, as illustrated inFIG. 2, a first half bead16surrounding the oil hole13and swollen to the cylinder head2side is formed on the oil seal plate P2, and the outer edge of the oil seal plate P2is formed so as to surround this first half bead16.

By means of the above configuration, the first half bead16seals the lubricant oil communicating through the oil passage when sandwiched between the cylinder block3and the cylinder head2.

The main plate P3is provided within a range sandwiched between the cylinder block3and the cylinder head2except the range on which the gas seal plate P1and the oil seal plate P2are provided.

A second half bead17surrounding the four combustion chamber holes11and the water hole14and swollen to the cylinder block3side is formed on the main plate P3.

These second half beads17are formed on the outside of the opening portion of the water jacket4awith substantially constant intervals and formed so as to avoid a position where the bolt hole12is formed.

By means of this configuration, the second half bead17seals the cooling water from the water passage when sandwiched between the cylinder block3and the cylinder head2.

That is, the cooling water communicating through the water passage is sealed by the full bead15of the gas seal plate P1and the second half bead17of the main plate P3.

Subsequently, the bolt hole12is located between the first half bead16of the oil seal plate P2and the second half bead17of the main plate P3, and a quarter bead18surrounding this bolt hole12and swollen to the cylinder block3side is formed.

The quarter bead18does not necessarily have to be provided.

According to the cylinder head gasket1having the above configuration, by connecting three types of plates with different plate thicknesses, that is, the gas seal plate P1, the oil seal plate P2, and the main plate P3, the cylinder head gasket1having a single layer can be obtained, and an inexpensive cylinder head gasket1can be obtained.

Moreover, since the plate thicknesses of the gas seal plate P1, the oil seal plate P2, and the main plate P3are different, when the cylinder block3and the cylinder head2are fastened by a bolt, different loads can be made to act on each of the plates P1to P3.

Furthermore, since each of the plates P1to P3is connected without overlapping in the first embodiment, a load does not concentrate on the overlapped portion as compared with the connection of the plates with overlapping, and plate-thickness management is facilitated.

Since the plate thickness of the gas seal plate P1is larger than the plate thicknesses of the oil seal plate P2and the main plate P3, the sealing properties in the periphery of the combustion chamber hole11can be obtained by increasing the load in the periphery of the combustion chamber hole11.

On the other hand, since the plate thickness of the oil seal plate P2is smaller than that of the main plate P3, a load concentrates on the main plate P3side in which the bolt hole12is drilled, and the load on the oil seal plate P2side can be alleviated, and a load to the first half bead16can be suppressed.

Therefore, even if a load around the oil hole13is increased by a thermal change during engine operation, collapse of the first half bead16is suppressed, and the lubricant oil from the oil passage can be sealed.

FIG. 4illustrates a sectional view of the cylinder head gasket1according to a second embodiment, and this view illustrates the same portion in the cylinder head gasket1of the first embodiment as the section illustrated inFIG. 2.

In the cylinder head gasket1according to this second embodiment, the plate thickness of the gas seal plate P1is the largest, while the plate thickness of the oil seal plate P2is larger than that of the main plate P3.

Since the other configurations are the same as those in the cylinder head gasket1in the first embodiment, further explanation will be omitted.

By means of the above-described configuration, since the plate thickness of the gas seal plate P1is larger than the plate thicknesses of the oil seal plate P2and the main plate P3similarly to the first embodiment, favorable sealing properties in the periphery of the combustion chamber hole11can be obtained.

On the other hand, since a load larger than that on the main plate P3acts on the oil seal plate P2, the lubricant oil from the oil hole13immediately after the engine is started can be sealed by increasing the load in the periphery of the oil hole13.

FIG. 5illustrates a sectional view of the cylinder head gasket1according to a third embodiment, and this view illustrates the same portion in the cylinder head gasket1of the first embodiment as the section illustrated inFIG. 2.

The cylinder head gasket1according to this third embodiment has a configuration in which two oil seal plates P2are laminated, and the total plate thickness of these two oil seal plates P2is smaller than the plate thickness of the main plate P3similarly to the first embodiment.

By means of the above-described configuration, since the plate thickness of the gas seal plate P1is larger than the plate thicknesses of the oil seal plate P2and the main plate P3similarly to the first embodiment, a load in the periphery of the combustion chamber hole11can be increased, and favorable sealing properties can be obtained.

Moreover, since the plate thickness of the oil seal plate P2is smaller than that of the main plate P3, a load on the half bead formed on the oil seal plate P2can be suppressed by fastening of a bolt, and the lubricant oil from the oil passage can be sealed by suppressing collapse of the half bead.

FIG. 6illustrates a sectional view of the cylinder head gasket1according to a fourth embodiment, and this view illustrates the same portion in the cylinder head gasket1of the first embodiment as the section illustrated inFIG. 2.

The cylinder head gasket1according to this fourth embodiment has a configuration in which two gas seal plates P1are laminated, and though the plate thickness of each gas seal plate P1is smaller than that of the main plate P3, the total plate thickness of these two gas seal plates P1is larger than the plate thicknesses of the main plate P3and the oil seal plate P2similarly to the first embodiment.

The full bead15is formed toward the cylinder head2and the cylinder block3on each of the two gas seals, respectively.

By means of the above-described configuration, since the plate thickness of the gas seal plate P1is larger than the plate thicknesses of the oil seal plate P2and the main plate P3similarly to the first embodiment, a load in the periphery of the combustion chamber hole11can be increased, and favorable sealing properties can be obtained.

Moreover, by reducing the plate thickness of a single gas seal and by forming the full bead15on each of the two gas seals, the combustion gas can be sealed by the two full beads15, and a follow-up performance of the cylinder head2and the cylinder block3to a gap can be improved.

Since the plate thickness of the oil seal plate P2is smaller than that of the main plate P3similarly to the first embodiment, a load to the half bead formed on the oil seal plate P2can be suppressed by fastening of a bolt, and the lubricant oil from the oil passage can be sealed by suppressing collapse of the half bead.

Regarding the oil seal plate P2, the plate thickness of the oil seal plate P2may be set larger than that of the main plate P3as in the second embodiment, whereby the lubricant oil from the oil hole13immediately after the engine is started can be sealed.

FIG. 7illustrates a sectional view of the cylinder head gasket1according to a fifth embodiment, and this view illustrates the same portion in the cylinder head gasket1of the first embodiment as the section illustrated inFIG. 2.

The cylinder head gasket1of this embodiment has two layers of the cylinder head gasket1in the first embodiment, and the full bead15and the half bead are arranged so as to swell to the cylinder head2side and to the cylinder block3side, respectively.

By means of the above-described configuration, the effect of the cylinder head gasket1in the first embodiment can be obtained more effectively.

In this embodiment, the plate thickness of the oil seal plate P2may be set larger than that of the main plate P3similarly to the second embodiment.

FIG. 8illustrates a sectional view of the cylinder head gasket1according to a sixth embodiment, and this view illustrates the same portion in the cylinder head gasket1of the first embodiment as the section illustrated inFIG. 2.

The cylinder head gasket1of this embodiment has a configuration in which the connection portion between the gas seal plate P1and the main plate P3is located inside the opening portion of the water jacket4aas compared with the cylinder head gasket1in the first embodiment and moreover, a third half bead19swollen toward the cylinder head side is formed on the main plate P3at a position inside the opening portion of the water jacket4a.

As a result, the second half bead17provided on the main plate P3and a first half bead16provided on the oil seal plate P2are formed so as to swell to the cylinder block3side from the cylinder head2side, and the quarter bead18provided on the main plate P3is formed so as to swell to the cylinder head2side from the cylinder block3.

By means of the above-described configuration, the cooling liquid communicating through the water passage can be sealed by the second half bead17and the third half bead19provided on the main plate P3.

In each of the above-described embodiments, the half bead may be replaced by the full bead, respectively, whereby a higher sealing property can be obtained.

Moreover, in each of the above-described embodiments, each of the plates P1to P3are connected in a state they are abutted to each other without overlapping, but the end portions may be overlapped and connected to each other.

In that case, the connection position between the gas seal plate P1and the main plate P3is preferably within a range in which the water jacket4ais opened as in the above-described embodiment.

Moreover, in each of the above-described embodiments, if the positions of the bolt hole12and the oil hole13are close, the bolt hole12may be provided in the oil seal plate P2.

In this case, the bolt hole12separated from the oil hole12may be drilled in the plate having the same plate thickness as the oil seal plate P2, and the plate may be connected to the main plate.

Furthermore, in the case of an engine in which a water jacket is not formed in the cylinder block and a block-side passage and a head-side passage are formed at predetermined positions, the bead surrounding the water hole14which makes them communicate with each other may be provided to replace the second half bead17, as an outer bead, and to seal the cooling water.

REFERENCE SIGNS LIST